A ball whose mass is 0.4 kg hits the floor with a speed of 4 m/s and rebounds upward with a speed of 2 m/s. If the ball was in contact with the floor for 2 ms (2multiply10-3 s), what was the average magnitude of the force exerted on the ball by the floor?Favg = N. Calculate the magnitude of the gravitational force that the Earth exerts on the ball:mg = N

Explanation:

We shall apply concept of impulse

Impulse = Force x time

= Force x 2 x 10⁻³ N.s

impulse = change in momentum

change in momentum

= .4 x 4 - ( - .4 x 2 )

= 2.4

Force x 2 x 10⁻³  = 2.4

Force = 2.4 /  2 x 10⁻³

= 1.2 x 10³ N .

average magnitude of the force exerted by floor = 1.2 x 10³ N

If R be reaction force by earth

R - mg = 1.2 x 10³

R = 1.2 x 10³ + mg

= 1200 + .4 x 9.8

= 1200 +3.92

= 1203 .92 N .

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.