Emergency Physics Help

[2001]

Can anyone help me solve these 4 problems? I would greatly appreciate it and would give you a hug if it was possible. Even if you offer a little advice or only solve one.

1. Ball A, with a mass of 1.75 kg, moves with a velocity 3.90m/s. It collides with a stationary ball B, with a mass of 2.25 kg. After the collision, ball A moves in a direction 50.0 degrees to the left of its original direction, while ball B moves in a direction 40.0 degrees to the right of ball A's original direction. Calculate the velocity of each ball after the collision. Explain how you got your answer.

2. A 0.0420-kg hollow racquetball with an initial speed of 12.0m/s collides with a backboard. It rebounds with a speed of 6.0 m/s. If the contact time lasts for 0.040s, calculate the average force on the ball, and the total impulse on the ball. Justify your answer.

3. A toy car X of mass 0.450 kg moves along a frictionless surface with a velocity of 0.280 m/s. It collides with another toy car Y, with a mass of 0.200 kg and a speed of 0.150 m/s in the same direction. After the collision, toy car X continues to move in the same direction with a velocity of 0.166 m/s. Calculate the speed of toy car Y after the collision. Justify your answer.

4. A marksman at rest fires a 3.75 kg gun that expels a bullet of mass 0.0180 kg with a velocity of 193 m/s. The marksman's mass is 71.0 kg. What is the marksman's velocity after firing the gun? Justify your answer.

 

[Rici]

ok, this is just how you should do it, and not the actual calculations because I'm too lazy for that and think you should do it yourself.

1. First calculate the kinetic energy of Ball A (Ek= 1/2 mv^2). Then because Ball A is going at a 50 degrees and Ball B 40 degrees, you split up that energy to a respective 50/90 and 40/90. Then when you know that you use Ek=1/2 mv^2 to calculate the velocities of the balls.

2.Can't help you there because I'm not really sure what is meant by impulse. Only advice I can give is that you again calculate the kinetic energy, then the kinetic energy the ball has when going upwards, so the difference between the two goes into the 'bounce'. Then use that to calculate the average force.

3.Again, all transverse all to kinetic energy. Initial kinetic energy of car X- kinetic energy after collision = kinetic energy that went into car Y. Initial kinetic energy car Y+ collision energy = total kinetic energy car Y, use that to calculate the new velocity.

4. Action= -Reaction. The bullet blasts of with a certain kinetic energy, but for it to do that, it needs to push it back towards the gun+marksmen. So calculate the kinetic energy of the bullet, then use that number to calculate the velocity of the marksman(don't forget to add up the 71 and 3,75 kg)