(25 Points) PLEASE HELP Two objects collide elastically at a relative velocity of 50 ms -1. Relative to an observer, which of these are not possible velocities for the two objects after the collision?

A. 50 ms-1 and 0 ms -1

B. 10ms-1 to the right and 60 ms-1 to the right

C. 20ms-1 to the left and 30ms-1 to the right

D. 0ms -1 and 0 ms -1

And why?

Aparticle initially moving east with a speed of 20.0 m/s, experiences an acceleration of 3.95 m/s, north for a time of 8.00 s. what was the speed of the particle after this acceleration, in units of m/s? give the answer as a positive number.

Afisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. it takes a time of 2.20 s for the boat to travel from its highest point to its lowest, a total distance of 0.670 m . the fisherman sees that the wave crests are spaced a horizontal distance of 5.80 m apart. (a) how much is the wavelength? (b) find the period of the wave. (c) how fast are the waves traveling? (d) what is the amplitude a of each wave?

What would be the strength of earth's gravitational field at a point where an 80.0 kg astronaut would experience a 80% reduction in weight