Download 05 Friction and Net Force Practice

Friction and Net Force Practice
1. A smooth wooden block is placed on a smooth wooden tabletop. You find that you must exert a
force of 14 N to keep the 40 N block moving at a constant velocity.
a. What is the coefficient of kinetic friction for the block and table?
b. If a 20 N brick is placed on the block, what force will be required to keep the block and
brick moving at a constant velocity?
2. The acceleration for a particular car is -15 m/s2. The mass of the car is 1250 kg. Find the friction
force of the car when it is decelerating.
3. A football weighs 13.36 N.
a. What is the mass of the ball?
b. What is the acceleration of the ball if an upward force of 53 N is applied?
4. A space shuttle has a mass of 3.5 x 106 kg. At lift off the engines generate an upward force of
4.5 x 107 N.
a. What is the weight of the shuttle?
b. What is the acceleration of the shuttle when launched?
5. The average acceleration of the shuttle during its 15 minute launch is 25 m/s2. What velocity
does it attain?
6. If you use a horizontal force of 55 N to slide a 21 kg wooden crate across a floor at a constant
velocity, what is the coefficient of kinetic friction between the crate and the floor?