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Physics Chap 9 Review

Physics Chap 9 Review

Assessment

Presentation

Science

10th - 12th Grade

Hard

Created by

Kurt Trout

FREE Resource

7 Slides • 0 Questions

1

Physics Chap 9 Review

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2

Things you need to know, and will be provided with

  • p= momentum

  • p=mv. OR....

     Δ\Delta  p = m  Δv\Delta v     or p= m(v final - v initial)

  • So, impulse theorem is F Δ\Delta  t =  Δ\Delta  p   or Ft=m(v final - v initial)

  • In a collision where the objects stick together.

  • MaVa + MbVb = Ma+b Vf

  • And last, recoil.   MaVa = -MbVb

3

Lets look at a few

  • A 5500-kg freight truck accelerates from 4.2 m/s to 7.8 m/s in 15.0 s by the application of a constant force

  • What change in momentum occurs?

  • so, p=m(Vf-Vi). or 5500(7.8 - 4.2)

  • How large a force is exerted?

  • Ok took 15 secs, so..

  • Ft = m(Vf-Vi). or. F=m(Vf -Vi)/t. 5500(7.8-4.2)/15

4

What will a level 4 look like?

  • Small rockets are used to slightly adjust the speeds of spacecraft. A rocket with a thrust of 35 N is fired to change a 72,000-kg spacecraft’s speed by 63 cm/s. For how long should it be fired?

  • Ok still pretty simple, but where is the catch?

  • Ft=change in p. so t=M9Vf-Vi)/F.

  • catch is, what is the velocity in???

5

Another example

  • SpongeBob throws a spatula in a fit of anger at Mr. Krabs standing at the counter who catches it and flies backwards at some speed. How fast did Spongebob throw the spatula?(

  • Assume MsVs + MkVk = Ms+k x Vf

  • (s= spatula and k = mr krabs, and Vf is velocity final)

  • Rearrange to Vs = (Ms+k)(Vf)/Ms

  • remember, Mr. Krabs wasn't initially moving

6

Last one

  • Diego and Keshia are on in-line skates. They stand face-to-face and then push each other away with their hands. Diego has a mass of 90.0 kg, and Keshia has a mass of 60.0 kg. Keshia flies away at 5.5 m/s. How fast then did Diego go?

  • MdVd = -MkVk

  • So, Vd= -(MkVk)/Md



7

Things to remember

  • Just use the right equation, and rearrange

  • Keep in mind V final or V initial, but if at rest, it is 0!

  • Watch units!!! kg, m/s.....

Physics Chap 9 Review

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