AP Physics with Hansenator - Midterm Exam Solutions

True/False (5 pts each):

F 1. A car travels around a track once, of radius 1 m, and stops, its displacement is 2π m. 0 m
T 2. The displacement of an object is how far it is from its initial position.
F 3. The area under a velocity versus time graph is the acceleration. Displacement
T 4. The area under a force versus time graph is the work done.
T 5. When an object speeds up, its acceleration is in the direction of motion.
T 6. In projectile motion, the acceleration is constant.
T 7. In projectile motion, at the top of the curve the velocity in the y-direction is zero.
F 8. In projectile motion, velocity in the x-direction is zero. Sometimes
T 9. Two objects dropped from the same height will hit the ground at the same time neglecting air resistance.
F 10. There are 10 significant digits in 1050000000 meters. Three
F 11. An object in equilibrium (forces) will not move. Will not accelerate
T 12. Newton’s Second Law states force is equal to mass times acceleration.
F 13. If an object is in equilibrium (zero acceleration), then there are no forces acting on it. There can be
T 14. The unit for Newtons is kg∙m/s^2.
F 15. The unit for power is Watts, or kg∙m^2/s^2. kg m^2/s^3
T 16. Normal force is how hard the surface presses back up on an object.
F 17. Normal force is always equal to the weight of an object. Not Necessarily
F 18. Friction is a force that acts in the same direction of the motion. Opposite
F 19. If a ball rolls of a table at 5 m/s, the initial velocity in the y direction is 5 m/s. x-direction
T 20. The angle that gives a projectile the farthest distance is 45°.

Short Answer (10 pts each):

A bullet is fired straight upwards with an initial velocity of 850 ft/s. How high did it go in meters?
A golfer on the moon (g = 1.62 m/s^2 ) drives a ball at an angle of 30 degrees with an initial velocity of 22 m/s. How far does it go?
Consider the two weights in the pulley system. Find the acceleration of the system.
Assume the 8.0-kg box moves. Find the acceleration if the kinetic friction is μ=.100.
Draw the velocity vectors at the points labeled for the projectile.

Notice that the velocity in the x-direction is constant and the velocity in the y-direction is affected by gravity, slowing it from positive speed to negative speed.
Draw a free body diagram to model the situation. Assume the box moves.
Use the conservation of energy to solve the following problem. A basketball is shot from 1.5 m with an initial speed of 4 m/s. How fast is it moving 3 m from the ground?