Two balls having different masses reach the same height when shot into the air from
the ground. if there is no air resistance, which of the following statements must be
true? (more than one statement may be true.)
(a) both balls left the ground with the same speed.
(b) both balls left the ground with the same kinetic energy.(c) both balls will have the same gravitational potential energy at the highest point.
(d) the heavier ball must have left the ground with a greater speed than the lighter
ball.
(e) both balls have no acceleration at their highest point.

At 20∘c, the hole in an aluminum ring is 2.800 cm in diameter. you need to slip this ring over a steel shaft that has a room-temperature diameter of 2.804 cm . 1. to what common temperature should the ring and the shaft be heated so that the ring will just fit onto the shaft? coefficients of linear thermal expansion of steel and aluminum are 12×10−6 k−1 and23×10−6 k−1 respectively.

Beryl states that insulation with the smallest possible thermal conductivity is best to keep a house warm in winter, but worst for keeping a house cool in summer. sapphire insists the reverse is true: low thermal conductivity is good in the summer, but bad in the winter. which one, if either is correct? a. beryl, because low thermal conductivity results in low heat transfer. b. beryl, because low thermal conductivity results in high heat transfer. d. sapphire, because low thermal conductivity results in high heat transfer. e. neither, because low heat transfer is desirable both in summer and in winter.

Which is an example of an exothermic process?