What would be an ideal experiment to test how different types of surfaces affect friction?
a) two objects of equal weight placed on two glass surfaces of equal lengths.
b) two objects of equal weight placed on two glass surfaces of unequal lengths.
c) two objects of equal weights placed on a glass surface and a wooden surface.
d) two objects of different weights placed on two wooden surfaces of unequal lengths.

According to social exchange theory, altruistic behaviors benefit the individual who performs them. t/f

1. consider the case in which air fills air shocks on a truck trailer. the pressure in the shocks is 2 mpa. the temperature is 300 k. the diameter of the shock piston is 10 cm and the initial length of the cylindrical cavity containing the compressed air is 40 cm. a. the truck is gradually loaded over a period of a day in a static setting. the temperature is held constant for the atmosphere and thus for the gas shock. calculate the compressibility of the air in the shock for this condition when the truck is initially being loaded. b. if the shocks were loaded in a dynamic setting by driving over bumps, what would be the compressibility? state your assumption. c. what is the initial load on the shock if the shock is in an atmospheric 100 kpa? d. if the shock is compressed using the process described in part a, and the air shock compressed air cavity length decreases to 20 cm, what is the additional load applied to the shock?

What is a subatomic particle with a negative charge and very little mass?