What is a difference between speed and velocity?
A. Speed includes direction and the rate of travel.
B. Velocity includes the direction of travel
whereas speed does not.
C. Velocity includes the time during which travel
occurred.
D. None of the above

When air rushes out of a balloon, the balloon itself
starts to move in the other direction. Which of
Newton’s laws does this describe and why?
A. 1st
B. 2nd
C. 3rd
D. 1st and 2nd

A force that slows objects down and opposes
motion is called
A. Net force
B. Centripetal force
C. Gravity
D. Friction

1: D
2: C
3: B
4: A

16. a brave but inadequate rugby player is being pushed backward by an opposing player who is exerting a force of 800 n on him. the mass of the losing player plus equipment is 90.0 kg, and he is accelerating at 1.20m/s2 size 12{1 "." "20"" m/s" rsup { size 8{2} } } {} backward. (a) what is the force of friction between the losing player’s feet and the grass? (b) what force does the winning player exert on the ground to move forward if his mass plus equipment is 110 kg? (c) draw a sketch of the situation showing the system of interest used to solve each part. for this situation, draw a free-body diagram and write the net force equation.