If the force acting on an object is negative, what two directions could the force be acting?
Left and down
100
Horsepower is a unit for what value?
Power
100
What does energy share its units with?
Work
100
Name the two units that can be used for both impulse and momentum.
Ns and kgm/s
200
What is the difference between average velocity and instantaneous velocity?
Average velocity depends on the total displacement and the total time. Instantaneous velocity is how fast you are going at a particular moment. Sometimes, these can be the same.
200
What is the definition of net force?
Net force is the sum of all forces acting on an object.
200
Using the picture in the envelope marked "3", determine which person does more work to move his suitcase.
Person A does more work.
200
What is Mechanical Energy (ME)?
Mechanical energy is the combination of gravitational potential energy and kinetic energy.
200
What is the momentum of a 8 kg object moving with a constant velocity of 2.25 m/s?
18 Ns
300
What is the y-velocity of a projectile at the highest point?
0 m/s
300
What is Newton's First Law?
An object in motion will stay in the SAME motion, and an object at rest will stay at rest, unless an unbalanced, outside force acts on the object.
300
Which concept needs time in order to calculate it: work or power?
What is the difference between an inelastic collision (NOT perfectly inelastic) and an elastic collision?
Both collisions have objects enter and leave separately, but in inelastic collisions, the objects give off energy as heat or sound during the collision.
400
What are the accelerations in the x and y directions of a ball at the highest point in projectile motion?
0 and 10 m/s/s
400
An object rolls past you at a constant speed. What can you say about the forces acting on the object?
A constant velocity means no acceleration, and no net force. So, either there are no forces acting on the object OR the net force is 0 N.
400
You spend 10 minutes staring at a homework problem, and you still haven't figured anything out. Have you done any "work"? Why or why not?
If you haven't accomplished anything, you haven't done any work.
400
You've calculated the mechanical energy of a falling apple to be 50 J right now. How does the ME of the apple as it started to fall compare to the ME of the apple just before it hits the ground?
ME is conserved in free fall, so ME = 50 J during the ENTIRE fall.
400
Give an example of when you would want both a big force and a long time in a collision.
When your goal is to make a big change of momentum (often in sports - hitting a baseball, tennis ball or golf ball)
500
Using the picture in the envelope marked "1", determine the height of the cliff.
y = 12.8 m
500
Using the picture in the envelope marked "2", determine the acceleration of box A.
5 m/s^2
500
You use 20 J of energy to lift a 5 kg box 30 cm off of a table. How efficient is your lifting process?
0.75 or 75%
500
Using the picture in the envelope marked "4", determine the velocity of the pineapple.
7 m/s
500
Using the picture in the envelope marked "5", determine the final velocity of the smaller ball.