Jennifer hits a stationary 200. gram ball and it leaves the racket at 40. m/s. If time lapse photography shows that the ball was in contact with the racket for 40. ms:
(a) What average force was exerted on the racket?
(b) What is the ratio of this force to the weight of the ball?
Question 2The statement that heat energy cannot be completely transformed into work is a statement of which thermodynamic law?
A) fourth
B) zeroth
C) second
D) third
E) first
Question 3In a liquid at a given temperature, the molecules are moving in every direction, some fast, some slowly. Electrical forces of adhesion tend to hold them together.
However, occasionally one molecule gains enough energy (as a result of collisions) so that it pulls loose from its neighbors and escapes from the liquid. Which of the following can best be understood in terms of this phenomenon? A) Increasing the atmospheric pressure over a liquid will cause the boiling temperature to decrease.
B) If snow begins to fall when you are skiing, you will feel colder than you did before it started to snow.
C) When a large steel suspension bridge is built, gaps are left between the girders.
D) When you step out of a swimming pool and stand in the wind, you will get colder than you would if you stayed out of the wind.
E) A hot water bottle will do a better job of keeping you warm than will a rock of the same mass heated to the same temperature.
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