A 30kg cart moving at 20 m/s collides elastically with a 20kg cart moving at 10m/s. If after the collision the 30 kg cart is 12m/s, then what is the velocity of the 20 kg cart after the collision?

The graph describes the motion of an object. the object moves with from a to b. it from b to c. it moves with from c to d.

Which statement is true if the refractive index of medium a is greater than that of medium b? a. total internal reflection is possible when light travels from air to medium b to medium a. b. total internal reflection is possible when light travels from medium a to medium b. c. total internal reflection is possible when light travels from medium b to medium a. d. total internal reflection is possible when light travels from air to medium a. e. total internal reflection is possible when light travels from air to medium b.

Ultraviolet radiation is dangerous because it has a high enough energy to damage skin cells. what is the best explanation of the relationship between wavelength and wave energy? a) wave energy is related only to frequency, not wavelength. b) longer wavelengths have lower frequencies but higher energy. c) the shorter the wavelength, the lower the frequency and the higher the energy. d) the shorter the wavelength, the higher the frequency and the higher the energy.