Two identical cars, each traveling at the same velocity, and having the same mass come to a stop
Car A stops in 0.3 seconds.
Car B stops in 5 seconds.
Which of the following statements is TRUE?
O Car A has less momentum and experiences less force than Car B.
O Car A has the same change in momentum but experiences more force than Car B.
Car A has the same change in momentum but experiences less force than Car B.
© Car A has the same change in momentum and experiences the same force as Car B.
1 2

Answer:

The second option - same change in momentum, different force

Explanation:

They experience the same change in momentum, but the force on car A is greater.

p=m*v

Impulse, or change in p=F*t

We know the cars have the same change in momentum, because they both go from the same initial momentum (p=mv), to zero momentum. Therefore, both experience the same change in momentum. Since the time is different, but the change in momentum is the same, the force has to be different.

For example: if both cars had 200 kg*m/s of momentum at the start, and 0 at rest, the impulse is 200 kg*m/s

So,

p(a)=    200=F(0.3)

p(b)=    200=F(5)

Which force has to be greater to make the equations true? The force for Car A, of course!