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# Physics help urgent watch

1. A bullet of mass 3.0*10^-2 is fired at a sheet of plastic of thickeness 0.015. the bullet enters the plastic with a speed of 200ms-1 and emerges from the other side with a speed of 50ms-1

calculate the loss of ke of the bullet as it passes through i got 562.6

the average frictional force exerted by the plastic on the bullet; idk how to answer this plz help
2. In normal motion we assume there is no resistive force to the bullet.

When the bullet enters the sheet it experiences a frictional force, which causes a net force to act on the bullet, slowing it down.

A resultant force on an object with mass will cause an acceleration.

What is a formula for acceleration? You have enough information to calculate the acceleration (in this case, deceleration) of the bullet.

Using this acceleration, refer to Newton's 2nd Law to obtain force
3. (Original post by yeah1106)
^
Part a) use ΔE = 1/2m(v2-u2)

Part b) use W.D = Fd

Does that help?
4. (Original post by Alexion)
Part a) use ΔE = 1/2m(v2-u2)

Part b) use W.D = Fd

Does that help?
Actually this is much simpler

Use this expression for part b
5. (Original post by Alexion)
Part a) use ΔE = 1/2m(v2-u2)

Part b) use W.D = Fd

Does that help?
Thx so much i got the right answer

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