Physics Practice Test for Forces and Newton’s Laws
Solutions

1. State any two of Newton's Laws in your own words and explain them using examples.
2. Consider a block of mass equal to your mass lying on a horizontal surface (μ_k=0.500 and μ_s=0.800 between the block and the surface). 
1. A rope is used to pull on the block with a force of magnitude 100N directed to the right.  Draw the free body diagram for the block showing all the forces and labeling them according to their type (normal, tension, weight, static friction, etc.) and value.
2. Describe the reaction force for each of the forces.  (Think Newton’s Third Law.)
3. What is the maximum force that can be applied by the rope without the block moving?
4. What will happen if the rope applies a force twice the magnitude of what you found in answer c)? (Be explicit. 
5. How far will the block in question c) have traveled if it starts from rest and is pulled with that force for 3.0 s?
3. Two blocks are hung over a frictionless, massless pulley, with a massless rope so that each mass hangs on one side of the pulley and the tension is constant throughout the rope.  The block on the right has a mass equal to the day of your birth (if you were born August 21^st, use a mass of 21 kg).  The block on the left has a mass of 40kg. Draw a free body diagram for each block, assuming that the heavier block causes the pair of them to accelerate in its direction with an acceleration = a.
1. Write the pair of equations you get by applying Newton’s Second Law (N2) to each diagram.
2. Solve the equations to get:

i.                     The tension in the rope.

ii.                   The acceleration of the blocks.

4. A block of your mass is sliding down a ramp inclined 45˚ to the horizontal.
1. Draw the free body diagram for the block, choose and show a coordinate frame and draw an arrow representing the acceleration down the ramp labeled a.
2. Write out the equations in the x and in the y directions from the diagram and using N2.
3. Solve the equations to find:

i.         The normal force on the block.

ii.       The acceleration of the block.

4. Bonus: If μ_k=0.8 and μ_s=1.2 between the block and the ramp

i.         What will happen if the block is initially at rest?

I.        Find the friction force and the acceleration, if there is any.

ii.       What will happen if the block is initially in motion?

I.        Find the friction force and the acceleration, if there is any.