8.29 Changing Mass. An open-topped freight car wh 24,000 kg is coasting without friction along a level track. It is rain- ing very hard, and the rain is falling vertically downward. Origi- nally, the car is empty and moving with a speed of 4.00 m/s. (a) What is the speed of the car after it has collected 3000 kg of rain- water? (b) Since the rain is falling downward, how is it able to affect the horizontal motion of the car?

A 3.30-kg steel ball strikes a wall with a speed of 11.0 m/s at an angle of 0 = 60.0° with the surface. It bounces off with the same speed and angle (see figure below). If the ball is in contact with the wall for 0.200 s, what is the average force exerted by the wall on the ball? (Assume right and up are the positive directions.) Fx N Fy y

Arnima is driving a 1250 kg car at 120 km/h and runs into a 520 kg moose eating grass (stationary). The road is W 22° S. Upon impact, the moose dies - the collision is inelastic. Find the final velocity of the moose and car.

A puck of mass miis moving along a frictionless table at speed viin the +x- direction when it is hit simultaneously by 2lumps of clay, each of mass m2. Both lumps are traveling at a speed of v2when they hit the puck. One is traveling in the -x-direction, while the other one is dropped from above the table in the -y-direction. The puck and lumps of clay stick together. What is the speed of the puck and clay after the collision? Express your answer in terms of mim2v1and v2only. HINT: Write down the initial momentum of the puck m1. In which direction(s) is momentum conserved(i.e. in which direction(s) is there no net external force? Keep in mind that the table can provide an external normal force).Add the momenta of the lump(s) of clay for which momentum is conserved to your initial momentum. At the end of the day, the puck and both lumps of clay stick together so the final momentum is pf=(m1+m2+m2)vf. Set the initial and final momenta equal to each other and solve forvf.