14. Determine a skier's velocity in kilometers per hour if it takes her 1.7 minutes to ski down a 1.67 km slope.
15. On a bus traveling north at 15 m/s, a child stands up and walks toward the back of the bus at 3
m/s. What is the child's resultant velocity?
16. Calculate the average acceleration of a car that changes speed from 0m/s to 15 m/s in 5s.
17. Calculate how long it takes for a stone falling from a bridge with an average acceleration
downward of 9.8 m/s to hit the water. The stone starts from rest and hits the water with a
velocity of 12.3 m/s
18. What are the two main types of kinetic friction?
19. Why is it easier to move a chair with wheels across a floor than a chair without wheels?
20. Analyze the following situations, and indicate whether the forces are balanced or unbalanced:
a. A skydiver accelerating downward
b. a motorboat coasting at a constant speed
c. A bike leaning against a tree
21. Identify the following examples of friction as unwanted or necessary
a. friction between a cast-iron pan and the food in the pan
b. friction between bones in a joint
c. friction between tires and the road
22. The Concorde is the fastest supersonic passenger jet. How long would the Concorde take to
travel 6,265 km between New York City and London, assuming that the jet travels at its
maximum speed of 2.150 x 10km/hr during the entire trip?
23. The solid-fuel rocket boosters used to launch a space shuttle can lift the shuttle 45 km above
Earth's surface. During that time, the shuttle undergoes an almost constant total acceleration of
6.25 m/s', so that its speed increases from rest to about 750 m/s. How long does it take for the
shuttle to reach this speed