Collected Problems for Test 2

Problem #7 (Due 9/20 Friday by 8:00 a.m.)
A constant net force that has a magnitude of 135.5 N is exerted on a 26.7 kg object that is initially not moving.
a. Draw a free body diagram of the object. Assume there is only the net force of 135.5 N acting on the object.
b. What acceleration does this force produce?
c. Sketch a position vs. time graph for the object.
d. Sketch a velocity vs.. time graph for the object.
e. How far does the the object travel in 8.82 s?

Problem #8 (Due 9/24 Tuesday by 8:00 a.m.)
Suppose two boxes sit next to one another on a smooth horizontal surface. Box A has a mass of 4.7 kg and box B has a mass of 7.3 kg. A 4.62 N horizontal force is applied to box A as shown.

a. Draw a free body diagram for box A.
b. Draw a free body diagram for box B.
c. Find the magnitude of the contact force (the force box A pushes on box B) between the two boxes.
d. If the 4.62 N applied force is instead applied horizontally to box B rather than box A is the contact force the same, greater, or less than the contact force for part c? Verify by calculating the contact force.


Problem #9 (Due 9/27 Friday by 8:00 a.m.)
Three spheres are arranged as shown in the diagram. The first sphere, of mass m₁ = 12. 7 kg is located at the origin; the second sphere, of mass m₂ = 4.44 kg is located at (-6.00, 0.00) m ; and the third sphere, of mass m₃ = 8.03 kg is located at (0.00, 5.00) m. What is the net gravitational force on the sphere located at the origin?

Problem #10 (Due 10/1 Tuesday by 8:00 a.m.)

A 1.02 kg block is pressed against a vertical wall by a force of 11.7 N as shown below.
a. Draw a free body diagram of the block if it is not moving but on the verge of moving upwards.
b. Draw a free body diagram of the block if it is not moving but on the verge of moving downwards.
c. Suppose the block is initially moving upwards. If the coefficient of kinetic friction is .20 what is the acceleration of the block? Start with a new free body diagram.

Problem #11 (10/4 Friday 8:00 a.m.)
The two blocks below are attached by a string. They slide down a 20.1^o incline. Box A has a mass of m_A = .81 kg and box B has a mass of m_B = .26 kg. The coefficient of kinetic friction between box A and the incline is .302 and the coefficient of kinetic friction between box B and the incline is .203.
a. Sketch a free body diagram of each box.
b. Determine the acceleration of the boxes down the incline.
c. Determine the tension in the string.

Problem #12 (Due 10/9 Wednesday 8:00 a.m.)
A toy car of mass .073 kg is compressed against a spring shown below. The spring is compressed 9.1 cm and has a spring constant of 9.83 N/m. When the car is released it moves across a frictionless table and then goes off the 22^o ramp. Determine how far from the edge of the table the car lands if the ramp is 1.22 m above the floor. Neglect any height change due to the ramp.