Homework: Forces Name: _____________________ Section: ______
Copyright 2008 by S. Kanim, M. Loverude, and L.Gomez 1
1. For each situation below, draw a free-body diagram of the object that is identified. Label each force that you have included in your free-body diagram to indicate (1) the type of force, (2) the object on which the force is exerted, and (3) the object exerting the force. i. A block that is at rest on a ramp. ii. A block that is tethered by a string to a horizontal ramp.
The block is at rest, and there is no friction between the block and the ramp.
iii. The rag in the diagram. The window washer is using a stick to push the rag
upwards along the window.
2. A student has a weight of 750 Newtons. What is the mass of the student? Show your work.
3. What is the gravitational force exerted on a metal cube of mass 150 grams? Show your work.
µ = 0
Lab Homework 4: Forces
4. The massless string shown at right is wrapped around two
pulleys. It is tethered to the desk on one side and a mass hangs from the other side. Rank the tensions at the six labeled points along the string. Explain how you determined your ranking.
5. A person stands on a ladder that is resting against a wall. (Assume that there is no friction between the ladder and the wall.) Draw a free-body diagram of the ladder in the space to the right. Label each force that you have included as you did in question1. (Hint: The force on the ladder by the person is not a weight!)
6. In lab, you ranked the coefficients of friction for 3 carts
with different materials on the bottom: plastic, cork and fabric. In addition, you calculated the coefficient of kinetic friction for a cart with a cork bottom, and drew a free-body diagram for this cart as it was pulled at constant speed along a track. i. At right, draw a free-body diagram for the cart with the
fabric bottom as it slides at constant speed along the track. Sate how (if at all) this diagram is different from the one you drew for the cart with the cork bottom. Explain.
ii. Which forces in your free-body diagrams have the same
magnitude for the cork-bottomed and fabric-bottomed carts? Explain. iii. List all of the forces that are not the same for the two carts. For these forces, state which cart
has the larger force. Explain.
Hook and slotted masses
Cart with masses
Track Force probe