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Luba_88 [7]
2 years ago
15

A 1200 kg car is travelling qt 20m\s determine the work that must be done on the car by the frictional force of the brakes to st

op the car
Physics
1 answer:
Anestetic [448]2 years ago
4 0

Answer:

240000 Joules

Explanation:

Applying,

The work that must be done by the frictional force of the brake to stop the car must be equal to the kinetic energy of the car.

W = mv²/2.................. Equation 1

Where W = work done by the frictional force of the brake, m = mass of the car, v = velocity of the car.

From the question,

Given: m = 1200 kg, v = 20 m/s

Substitute these values into equation 1

W = (1200×20²)/2

W = 240000 Joules

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What happens when an object with a lower density is placed in a container with an
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The only thing that definitely happens in every such case is:
The container becomes heavier.
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2 years ago
ear the end of a marathon race, the first two runners are separated by a distance of 45.0 m. The front runner has a velocity of
sesenic [268]

Answer:

a) V_{2/1}=0.8m/s

b) The second runner will win

c) d = 10.54m

Explanation:

For part (a):

V_{2/1} = V_{2} - V_{1} = 0.8m/s

For part (b) we will calculate the amount of time that takes both runners to cross the finish line:

t_{1} = \frac{X_{1}}{V_{1}}=\frac{250}{3.45}=72.46s

t_{2} = \frac{X_{2}}{V_{2}}=\frac{250+45}{4.25}=69.41s

Since it takes less time to the second runner to cross the finish line, we can say the she won the race.

For part (c), we know how much time it takes the second runner to win, so we just need the position of the first runner in that moment:

X1 = V1*t2 = 239.46m  Since the finish line was 250m away:

d = 250m - 239.46m = 10.54m

6 0
3 years ago
Read 2 more answers
How do the tension of the cord and the force of gravity affect a pendulum?
LuckyWell [14K]

Answer:

<em>Force of gravity may not affect a pendulum during its equilibrium state</em>. But  the gravity can affect the pendulum when a force occurs in any direction of the bob connected to the cord that makes a swing sideways. The gravity of pendulum never stops, it always accelerates. So the gravity affects the pendulum acceleration and speed.    

<em>Similarly the tension in the cord will not affect the pendulum</em><em> </em>but if change in the length of the pendulum while keeping other factors constant changes the length of the period of pendulum. longer pendulum swings with lower frequency than shorter pendulums.    


6 0
2 years ago
Read 2 more answers
engineers are using computer models to study train collisions design safer train cars. They start by modeling an elastic collisi
Archy [21]

Answer:

The final velocity of the second car is 57 m/s south.

Explanation:

This is an elastic collision between two train cars. In this case, the total kinetic energy between the two bodies will remain the same.

The formula to apply is :

m_1v_1i +m_2v_2i=m_1v_1f+m_2v_2f

where ;

m_1=mass of object 1\\v_1i=initial  velocity object1\\m_2=mass of object2\\v_2i=initial velocity object 2\\v_1f=final velocity object 1\\v_2f=final velocity object 2

Given in the question that;

m_1=14650kg\\v_1i=18m/s\\m_2=3825kg\\v_2i=11m/s\\v_1f=6m/s\\v_2f=?

Apply the formula as;

m_1v_1i +m_2v_2i=m_1v_1f+m_2v_2f

{14650*18}+{3825*11} = {14650 *6} + {3825 * v₂f}

263700+42075=87900 + 3825v₂f

305775 =87900 + 3825v₂f

305775-87900 = 3825v₂f

217875=3825v₂f

217875/3825 =v₂f

56.96 = v₂f

<u>57 m/s = v₂f { nearest whole number}</u>

4 0
2 years ago
Read 2 more answers
1. Does the validity of the principle of conservation of momentum depend on the validity of Newton's 3rd law of motion?​
OverLord2011 [107]
I truly believe so, that’s a definite yes
8 0
3 years ago
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