Question

1) A 48.5-kg skater is standing at rest in front of a wall. By pushing against the wall she propels herself backward with a velocity of -1.46 m/s. Her hands are in contact with the wall for 1.00 s. Ignore friction and wind resistance. Find the average force she exerts on the wall (which has the same magnitude, but opposite direction, as the force that the wall applies to her). Note that this force has direction, which you should indicate with the sign of your answer.

Number

Units

No unitssmm/skgkg·m/sN

the tolerance is +/-2%

2) A model rocket is constructed with a motor that can provide a total impulse of 29.0 N·s. The mass of the rocket is 0.126 kg. What is the speed that this rocket achieves when it is launched from rest? Neglect the effects of gravity and air resistance.


Number_____ Units ______

No units°skgmm/sm/s^2Nkg·m/s or N·sJW

the tolerance is +/-2%

Answer 1

Headed theollos momentin toom Impulse Fare At=AP =mvp-muo Vo-O Fave - muf F well = - Pave --muf Fuar - - mue bt - 48.51-1-46) tos 70-80N F.At=mvp-mui vizo Foot = mve Fot ve = m = 29.0N'S 0-126 - 230.158m/