Chapter 6 Extra Credit (Mastering Physics)
Suppose we repeat the experiment from the video, but this time we use a rocket three times as massive as the one in the video, and in place of water we use a fluid that is twice as massive (dense) as water. If the new fluid leaves the rocket at the same speed as the water in the video, what will be the ratio of the horizontal speed of our rocket to the horizontal speed of the rocket in the video after all the fluid has left the rocket? (Ignore air resistance.)
2/3
How does Dr. Hewitt break the piece of wood?
He causes a change in momentum of his hand over a short period of time.
How is Dr. Hewitt able to break a piece of wood in his demonstration?
He moves his hand very quickly.
What would Dr. Hewitt need to have done to exert an even greater force than he did in his karate demonstration?
Increase the change in momentum, and decrease the time duration.
Predict what will happen if you reduce the magnitude of the velocity of the green truck to a magnitude smaller than that of the red truck.
The trucks will stick together after the collision and move to the left.
Click "Reset." Now, predict what will happen if you change the velocity of the red truck so that it has a magnitude smaller than that of the green truck but is negative.
The trucks will stick together after the collision and move to the right.
Click "Reset." Now, predict what will happen if you change the velocity of the red truck so that it has a magnitude smaller than that of the green truck but is positive.
The trucks will stick together after the collision and move to the right.
Click "Reset." Now, predict what will happen if you increase the mass of the green truck so that it is greater than the mass of the red truck.
The trucks will stick together after the collision and move to the right.
Before you click "Play," predict what will happen if the red and green truck with equal mass and equal magnitude of velocity collide.
The trucks will stick together after the collision and not move.
Suppose we replace both hover pucks with pucks that are the same size as the originals but twice as massive. Otherwise, we keep the experiment the same. Compared to the pucks in the video, this pair of pucks will rotate
at the same rate.
Imagine that you replace the block in the video with a happy or sad ball identical to the one used as a pendulum, so that the sad ball strikes a sad ball and the happy ball strikes a happy ball. The target balls are free to move, and all the balls have the same mass. In the collision between the sad balls, how much of the balls' kinetic energy is dissipated?
half of it
Now, consider the collision between two happy balls described in Part A. How much of the balls' kinetic energy is dissipated?
none of it
