Answer:
1 j
2 C
3 H
4E
5A
Explanation:
A robot standing on a cliff shoots a ball upwards with an initial speed of 30 m/s. What is the height of the cliff given that the ball reaches the bottom of the cliff 8 s after the shoot? (Take g = 10 m/s^2 and the height of the robot is negligible.)
A 25 m
B 45 m
C 80 m
D 145 m
Answer:
C 80 m
Explanation:
Given:
v₀ = 30 m/s
a = -10 m/s²
t = 8 s
Find: Δy
Δy = v₀ t + ½ at²
Δy = (30 m/s) (8 s) + ½ (-10 m/s²) (8 s)²
Δy = -80 m
The ball lands 80 m below where it started. So the height of the cliff is 80 m.
# A cheetah can start from rest and attain the velocity 72km/h in 2 seconds. Calculate the acceleration of cheetah
Answer:
[tex]10 \: [/tex] m/s ^2Explanation:
Solution,
When a certain object comes in motion from rest, in the case, initial velocity = 0 m/s
Initial velocity ( u ) = 0 m/s
Final velocity ( v ) = 72 km/h ( Given)
We have to convert 72 km /h in m/s
[tex]72 \: km \: per \: hour[/tex]
[tex] = 72 \times \frac{1000}{60 \times 60} [/tex]
[tex] = 20 [/tex] m/s
Final velocity ( v ) = 20 m/s
Time taken ( t ) = 2 seconds
Acceleration (a) = ?
Now,
we have,
[tex]a = \frac{v - u}{t} [/tex]
[tex]a = \frac{20 - 0}{2} [/tex]
[tex]a = \frac{20}{2} [/tex]
[tex]a = 10 [/tex] m/s ^2
Hope this helps...
Good luck on your assignment..
Maximum voltage produced in an AC generator completing 60 cycles in 30 sec is 250V. (a) What is period of armature? (b) How many cycles are completed in T/2 sec? (c) What is the maximum emf produced when the armature completes 180 0 rotation?
Answer:
a. 2 Hz b. 0.5 cycles c . 0 V
Explanation:
a. What is period of armature?
Since it takes the armature 30 seconds to complete 60 cycles, and frequency f = number of cycles/ time = 60 cycles/ 30 s = 2 cycles/ s = 2 Hz
b. How many cycles are completed in T/2 sec?
The period, T = 1/f = 1/2 Hz = 0.5 s.
So, it takes 0.5 s to complete 1 cycles. At t = T/2 = 0.5/2 = 0.25 s,
Since it takes 0.5 s to complete 1 cycle, then the number of cycles it completes in 0.25 s is 0.25/0.5 = 0.5 cycles.
c. What is the maximum emf produced when the armature completes 180° rotation?
Since the emf E = E₀sinθ and when θ = 180°, sinθ = sin180° = 0
E = E₀ × 0 = 0
E = 0
So, at 180° rotation, the maximum emf produced is 0 V.
One star has a temperature of 30,000 K and another star has a temperature of 6,000 K. Compared to the cooler star, how much more energy per second will the hotter star radiate from each square meter of its surface?
Answer:
The hotter star radiates 625 times more energy per second from each square meter of its surface
Explanation:
Temperature of the hotter star is 30000 K
temperature of the cooler star = 6000 K
From Stefan-Boltzmann radiation laws, for a non black body
P = εσA[tex]T^{4}[/tex]
where
P is the energy per second or power of radiation
ε is the emissivity of the body
σ is the Stefan-Boltzmann constant of proportionality
A is the area of the sun
T is the temperature of the sun
The sun can be approximated as a black body, and the equation reduces to
P = σA[tex]T^{4}[/tex]
For the hotter body,
P = σA([tex]30000^{4}[/tex]) = 8.1 x 10^17σA J/s
For the cooler body,
P = σA([tex]6000^{4}[/tex]) = 1.296 x 10^15σA J/s
comparing the two stars energy
==> (8.1 x 10^17)/(1.296 x 10^15) = 625
This means that the hotter star radiates 625 times more energy per second from each square meter of its surface
A 777-\text{ kg} kgstart text, space, k, g, end text object is accelerating to the right at 2 \text{ km}/\text{s}^22 km/s 2 2, start text, space, k, m, end text, slash, start text, s, end text, squared. What is the magnitude of the rightward net force acting on it
Answer: 14000 N
Explanation: i just did it on khan academy
A damped mass/spring system takes 14.0 s for its amplitude of the oscillator to decrease by a factor of 9. By what factor does the energy of the mass/spring system decrease over that time?
Answer:
The correct answer is "0.246".
Explanation:
Given that the amplitude is decreased by a factor of 9, then
[tex]A \rightarrow (A-\frac{A}{9} )[/tex]
[tex]A \rightarrow \frac{8A}{9}[/tex]
As we know,
Energy will be:
⇒ [tex]E_{1}=\frac{1}{2}KA^2[/tex]
and,
⇒ [tex]E_{2}=\frac{1}{2}K(\frac{8A}{9} )^2[/tex]
[tex]=\frac{64KA^2}{162}[/tex]
⇒ [tex]\Delta E=E_1-E_2[/tex]
On putting the estimated values, we get
[tex]=\frac{1}{2}KA^2-\frac{64KA^2}{162}[/tex]
⇒ [tex]\frac{\Delta E}{E}=\frac{\frac{20}{162}KA^2}{\frac{1}{2}KA^2}[/tex]
[tex]=\frac{40}{162}[/tex]
[tex]=0.246[/tex]
You and a friend are on a swing set and her swing is slightly longer than yours. If you both start swinging at the same time, from the same height, where will she be after you have completed one complete swing back and forth?
a. She will still be at the same height as you.
b. She will be slightly higher than you.
c. She will be slightly lower than you but moving downward away from you.
d. She will be slightly lower than you but moving upward toward you.
Answer:
d. She will be slightly lower than you but moving upward toward you.
Explanation:
Since your swing is slightly shorter than your friend's swing, then you will have more angular speed than your friend. Angular speed increases with a decrease in radius. The closer the body is to the center, the faster the body swings. By the time you would have completed one complete swing back and forth, your friend will just be moving towards you, and she will be slightly lower than you but moving upwards towards you. This principle is the same reason gymnasts pull their limbs closer to their body when they need to swing faster.
9) Of all the types of light the Sun gives off, it emits the greatest amount of light at visible wavelengths of light. If the Sun were to cool off dramatically and as a result start giving off mainly light at wavelengths longer than visible light, how would the frequency, energy, and speed of this light given off by the Sun also be different? Explain your reasoning.
Answer:
* most of the emission would be in the infrared part, the visible radiation would be very small.
*total intensity of the semition decreases that the intensity depends on the fourth power of the temperature
Explanation:
The radiation emitted by the Sun is approximately the radiation of a black body, if the Sun were to cool, the maximum emission wavelength changes
λ T = 2,898 10⁻³
λ = 2,898 10⁻³ / T
if the temperature decreases the maximum wavelength the greater values are moved, that is to say towards the infrared. Therefore the emission curve also moves, in this case most of the emission would be in the infrared part, the visible radiation would be very small.
Furthermore, the total intensity of the semition decreases that the intensity depends on the fourth power of the temperature according to Stefan's law
P = σ A eT⁴
What is the magnitude of the gravitational force between the earth and a 1 kg object on its surface? (Mass of the earth is 6 × 10 24 kg and radius of the earth is 6.4 × 10 6 m.)
Answer:
Explanation:
just use the gravational force equation which is G x m of earth x m of object divided by r squared (which is radius of earth)
pls help me with this question
Answer:
16 ms2 is the answer for this question
Pls someone I need it urgently and explain Solving and explanation so I can understand Thank you
Answer:
f = 6.37 Hz, T = 0.157 s
Explanation:
The expression you have is
y = 5 sin (3x - 40t)
this is the equation of a traveling wave, the general form of the expression is
y = A sin (kx - wt)
where A is the amplitude of the motion, k the wave vector and w the angular velocity
Angle velocity and frequency are related
w = 2π f
f = w / 2π
from the equation w = 40 rad / s
f = 40 / 2π
f = 6.37 Hz
frequency and period are related
f = 1 / T
T = 1 / f
T = 1 / 6.37
T = 0.157 s
Read the excerpt from "Justin Lebo.” When he got it home, he wheeled the junker into the garage and showed it proudly to his father. "Will you help me fix it up?" he asked. Justin's hobby was bike racing, a passion the two of them shared. Their garage barely had room for the car anymore. It was more like a bike shop. Tires and frames hung from hooks on the ceiling, and bike wrenches dangled from the walls. Based on the details in this excerpt, which word best describes the garage? inviting dangerous cluttered sparse
Answer:
cluttered
Explanation:
The correct word to describe the garage would be cluttered.
A place is said to be cluttered when it is filled with an untidy collection of material things. In this case, the garage is filled with materials such as bike wrenches, tires, frames, etc.
Inviting can also mean tempting, attractive, etc, and has no relevance to the condition of the garage as described in the excerpt.
Dangerous can also mean harmful, and not the right word to describe the garage.
Sparse can also mean scanty, scattered, and would be the opposite of the condition of the garage.
Correct answer: cluttered
Answer:
c. cluttered
Explanation:
a 15kg television sits on a shelf at a height of 0.3 m how much gravitational potential energy is added to the television when it is lifted to a shelf of height 1.0m?
Answer:
103 JoulesExplanation:
In this problem we are required to find the potential energy possessed by the television
Given data
mass of television m = 15 kg
height added above the ground, h= 1-0.3 = 0.7 m
acceleration due to gravity g = 9.81 m/s^2
apply the formula for potential energy we have
P.E= m*g*h
P.E = 15*9.81*0.7 = 103 Joules
Una tractomula se desplaza con rapidez de 69 km/h. Cuando el conductor ve una vaca atravesada enmedio de la carretera, acciona los frenos y se detiene 4 s después. Si la vaca estaba a 25 m de la tractomulacuando el conductor pisó el freno. ¿atropelló la vaca? Justifique su respuesta.
Answer:
Los datos que tenemos:
Rapidez: 69km/h
Tiempo que tarda en frenar = 4s.
Distancia inicial entre la tracto-mula y la vaca = 25m
Ok, la ecuación de desaceleración es:
D = (sf - si)/t
sf = velocidad final = 0m/s
si = velocidad inicial = 69km/h
t = tiempo = 4s
D = -69km/h/4s
ok, 1h = 3600s
D = (-69km/s)*1/(4*3600s) = -0.0048 km/s^2
Entonces la ecuación de aceleración es:
a(t) = -0.0048 km/s^2
Para la velocidad, integramos sobre el tiempo
v(t) = (-0.0048 km/s^2)*t + v0
donde v0 es la velocidad inicial, en este caso v0 = 69km/3600s = 0.0191km/s
v(t) = (-0.0048 km/s^2)*t + 0.0191km/s
Para la posición volvemos a integrar sobre el tiempo, esta vez suponemos la posición inicial igual a cero.
p(t) = (1/2)*(-0.0048 km/s^2)*t^2 + 0.0191m/s*t
Ahora, si p(t=4s) < 25m, esto implica que la tracto-mula no impacto con la vaca.
p(4s) = (1/2)*(-0.0048 km/s^2)*(4s)^2 + 0.0191km/s*4s = 0.038km
y 1km = 1000m
0.038km = 0.038*1000m = 38m
Entonces si, atropello a la vaca.
which discribes what a velocity/time graph would look like with no accelaration
explain translatory motion and give examples of various types of translatory motion
Answer:
Translatory Motion:
The motion of a body along a line is called Translatory Motion. The line may be straight or curved. There are three types:
1) Linear Motion:
Straight line motion of a body is called Linear Motion.
E.g. Movement of a car on a straight road.
2) Circular Motion:
Motion of a body along a circle is called circular motion.
E.g. Movement of a toy train along its circular track.
3) Random Motion:
The irregular motion of a body is called random motion.
E.g. Movement of a bee.
.......Hope it helps :)........
b. i. In a hydraulic press, a force of 200N is applied to master piston of area 25cm. If
the press is designed to produce a force of 5000N, determine the area of the slave
piston.
(4marks)
Answer:
625 cm²
Explanation:
The pressure is the same on both pistons.
F/A = F/A
200 N / 25 cm² = 5000 N / A
A = 625 cm²
the resistor of values 6 ohm,6 ohm are connected in series and 12 ohm are connected in parallel. the equivalent resistance of the circuit is
Answer:
The equivalent or total resistance of the circuit is 6
Explanation:
6 &6 are in series
6+6=r
r= 12
1/Rtotal= 1/12+1/2
1/Rt=2/12=1/6
Rt=6
In an oscillating LC circuit, the maximum charge on the capacitor is qm. Determine the charge on the capacitor, q, and the current through the inductor, I, when energy is shared equally between the electric and magnetic fields. Express your answers in terms of qm, L, and C.
Answer:
a. q = qm/√2 b. qm/√(2LC)
Explanation:
a. Charge on the capacitor
Let U₁ = energy in inductor and U₂ = energy in capacitor and U = total energy in circuit.
So, U₁ + U₂ = U.
Since the energy is shared equally between the capacitor and inductor, U₁= U₂,so
2U₂ = U
and U₂ = U/2
Now U₂ = q²/2C where q is the charge on the capacitor with capacitance C and
U = (qm)²/2C where qm is the maximum charge on the capacitor.
Since U₂ = U/2,
Substituting the values for U₂ and U, we have
q²/2C = [(qm)²/2C]/2
q² = (qm)²/2
taking square-root of both sides, we have
q = qm/√2
b. The current in the inductor
Since the energy in the capacitor equals the energy in the inductor,
1/2LI² = 1/2q²/C where L is the inductance of the inductor and I the current through it.
I² = q²/LC
taking square-root of both sides, we have
I = q/√LC
substituting the value of q from above, we have
I = qm/√2 ÷ √LC
I = qm/√(2LC)
how much heat is required to raise the temperature of 5kg of iron from 50°c to250°c
Answer:
462000J
Explanation:
Quantity of heat= mass x specific heat capacity of iron x change in temp
specific heat capacity of iron is 462J/Kg/K
change in temp = 250-50= 200°C
200°C is equivalent to 200K since 1°C is 1K
Q= mct
= 5x462x200
= 462000J
Two students are trying to measure how high a ball bounces when it is dropped from different heights. They dropped a ball from P and it bounced up till Q. They now have to record two measurements as shown below. Which measurements should they take?A.A B.B C.C D.D
Answer:
A.A
Explanation:
The balls usually bounce 60% of the original height because it stores 60% of the energy it had before the bounce. When a ball is dropped from a great height it has kinetic energy before it hits the ground which is the result of the bounce of ball. The size of ball does matter in this case, Large balls will bounce higher.
PLEASEEE HELP!!!!! I HAVE BEEN STRUGGLING FOR 2 DAYS
If i workout 90 minutes on earth, if I am on a rocket traveling 0.80c, according to the timer on the rocket, how long should I exercise?
Answer:
You should still workout 90 min.
The proper time is measured by a single clock in a single place.
The proper time on earth is 90 min.
The clock on the rocket is also in a single place in the frame of the rocket so you still need to workout for 90 min.
A 15 kg object is pulled by a force of 68 N. If the surface exerts a friction force of 23 N, with what acceleration does the object move?
Answer:
3 m/s²
Explanation:
Sum of forces in the x direction:
∑F = ma
68 N − 23 N = (15 kg) a
a = 3 m/s²
Train cars are coupled together by being bumped into one another. Suppose two loaded train cars are moving toward one another, the first having a mass of 270000 kg and a velocity of 0.325 m/s in the horizontal direction, and the second having a mass of 52500 kg and a velocity of -0.12 m/s in the horizontal direction. What is their final velocity?
Answer:
0.252 m/s
Explanation:
Applying the law of conservation of momentum,
Total momentum before collision = Total momentum after collision
Note: From the question, The collision between the car and the train is an inelastic collision and as such, both move with a common velocity after collision.
mu+m'u' = V(m+m')................... Equation 1
Where m = mass of the train, u' = initial velocity of the train, m' = mass of the car, u' = initial velocity of the car, V = common velocity after collision.
make V the subject of the equation
V = (mu+m'u')/(m+m')............... Equation 2
Given: m = 270000 kg, u = 0.325 m/s, m' = 52500 kg, u' = -0.12 m/s
Substitute these values into equation 2
V = [(270000×0.325)+{52500(-0.12)}]/(270000+52500)
V = 81450/322500
V = 0.252 m/s
Which may result from an increase in friction?
A: decreased traction
B: increased speed
C: reduced wear and tear
D: generation of heat
Answer:
Its Generation of Heat. or "D"Explanation:
Friction causes generation of heat and causes increased wear and tear.
The friction is a resistive force and is related to heat energy, so an increase in friction results in the generation of heat, so option D is correct.
What is friction?Two solid objects cannot roll or slide over one another due to the force of friction. Although frictional forces can be useful, such as the traction needed to walk without slipping, they can also present a large degree of resistance to motion. Automobile engines need about 20% of their power to overcome frictional forces in moving parts.
The fundamental source of friction between metals appears to be the adhesion forces between the contact zones of the surfaces, which are always microscopically uneven. Friction is produced by shearing, these "welded" seams, and the rubbing action of the rougher, tougher surface against the softer, smoother surface.
The friction is a resistive force trying to oppose the force applied As friction is related to heat when we increase the heat, the friction increases, and vice versa.
To know more about Friction:
https://brainly.com/question/28356847
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How many excess electrons must be distributed uniformly within the volume of an isolated plastic sphere 22.0 cmcm in diameter to produce an electric field of 1340 N/CN/C just outside the surface of the sphere?
Answer:
1.125x10^-10 electrons
Explanation:
Pls see attached file
correct answer will be marrk as braineast answer
Answer:
d) harvesting and threshing both.
Explanation:
Hope it helps you...
The density of water is 1000 kg m^3. What is the value expressed in gcm^-3 units? please help me..
(1) 1000 (2) 100 (3) 1 (4) 0.1 (5) 0.01
Here's the neat, cool way to convert units like this:
-- 1 kilogram = 1,000 grams
-- 1 meter = 100 centimeters
So . . . . .
(1000 kg/m³) x (1000 g/kg) x (1 m/100 cm)³ =
(1,000 kg/m³) x (1,000 g/kg) x (1 m³/1,000,000 cm³) =
(1,000 x 1,000 x 1 / 1,000,000) (kg-g-m³ / m³-kg-cm³) = 1 g/cm³
When a snowball turns into a puddle of
water, we know that
A. there is no change in the motion of the particles in the
puddle
B. the snowball's energy does not change; no phase change
occurs.
C. the snowball loses energy and changes from a liquid to a
solid,
D. the snowball gains energy and changes from solid to
liquid,
When a snowball turns into a puddle of water, we know that (the snow ball gains energy and changes from a solid to liquid).
This is correct due to the fact that particles of the snowball are gaining speed and so it is heating up, when the solid's temperature reaches the melting point, it will become a liquid.
Therefore, D is the correct answer.
A ball is thrown vertically upwards. It returns 6s later. Calculate : (1) the greatest height reached by the ball, and (2) the initial velocity of the ball. (Take g=9.8m/s2)
Answer:
greatest displacement = 44.1m
initial velocity= 29.4m/s
Explanation:
Greatest displacement
s=1/2at^2
= (9.8/2 ×9)m
= 44.1m
initial velocity
s=ut-1/2at^2
44.1= 3u -(1/2×9.8×9)
44.1=3u-44.1
3u=88.2
u=29.4m/s