# Physics-momentum/impluse

posted by becky

hi

well i have two questions i don't understand how to solve and all.

1) The front of a 1400-kg car is designed to absorb the shock of a collision by having a "crumple zone" in which the front of 1.2m of the car collapses in absorbing the shock of a collision. if a car traveling 25.0m/s stops uniformly in 1.2m, (a)how long does the collision last, (b) what is the magnitude of the average force on the car, and (c) what is the acceleration of the car in g's?

2) A 0.15kg baseball is thrown with a speed of 20m.s It is hit straight back at the pitcher with a final speed of 22m/s. (a) what is the impulse delivered to the ball? (b) find the average forece exerted by the bat on the ball if the two are in contact for 2.0 X 10^-3 seconds.

Thanks in advance..i really don't understand these two problems

a) To decelerate from velocity V to zero in a distance X, you need acceleration rate a given by
a = V^2/2X. The time to decelerate it
T = V/a = 2X/V

b)F = M a

c) divide a = V2/(2X) by g = 9.8 m/s^2 for the acceleration in g's.

2) (a) Use the fact that the momentum change equals the impulse. Consider the change of sign of the velocity when calculating the momentum change.
(b) Average force = (Impulse)/(time force is applied0

ohh i get it! thanks

wait umm for the second one... i don't understand ..like i know the process but yet its not working out for me..

for instance for part a) i don't understand like how to get it..i mean i know you would do FT=MV and then i don't know what exactly is to be done with..

b) ummm impulse/time..so it would be .15(2)/2.0*10^-3..but then it doesnt come out to the answer in the back of the book..

## Similar Questions

1. ### Physics

In a front-end collision, a 1400 kg car that has shock-absorbing bumpers can only withstand a maximum force of 75 kN before any sort of damage occurs.If the maximum speed for a car that is nondamaged in a collision is 10 Km/h, by how …
2. ### Physics

The front 1.20 m of a 1550 kg car is designed as a "crumple zone" that collapses to absorb the shock of a collision. (a) If a car traveling 26.0 m/s stops uniformly in 1.20 m, how long does the collision last?
3. ### science

A front end of modern cars are designed to crumple in the event of head-on-collision. (a) why are cars now designed to crumple on impact?
4. ### physical science

A front end of modern cars are designed to crumple in the event of head-on-collision. (a) why are cars now designed to crumple on impact?
5. ### Physics

The front 1.20 m of a 1,350-kg car is designed as a "crumple zone" that collapses to absorb the shock of a collision. (a) If a car traveling 22.0 m/s stops uniformly in 1.20 m, how long does the collision last?
6. ### physics

Please decide which of the following statements for car collisions are true or false. 1)Crumple zones on cars are parts of the front of the car that are designed to receive maximum deformation during a head-on collision. The essential …
7. ### Khudu secondary

Car A of mass 1 000 kg,stationary at a traffic light,is hit from behind by car B of mass 1 200 kg,traveling at 18 m.s-1. Immediately after the collision car A moves forward at 12 m.s-1. 1. Assume that linear momentum is conserved during …
8. ### Physics

Can anyone help with which formula I should use to solve this: During a head on car crash, the car is designed to slow down as its front end crumples. If a person can survive an acceleration of -33 m/s how far must the front end crumple …
9. ### Physics

A car is stationary at a stop sign when it is hit directly from behind by a truck of mass 3000kg which was travelling at a speed of 9 m/s immediately before the collision. The two vehicles lock together and move forward with an initial …
10. ### physics

The front 1.20 m of a 1,350-kg car is designed as a "crumple zone" that collapses to absorb the shock of a collision. (a) If a car traveling 21.0 m/s stops uniformly in 1.20 m, how long does the collision last?

More Similar Questions