What is the force of gravity on an 100kg person standing on the earth

A girl of mass 55 kg throws a ball of mass 0.80 kg against a wall. The ball strikes the wall horizontally with a speed of 25 m/s and it bounces back with this same speed. The ball is in contact with the wall 0.050 s.

On a cloudless day the sky is blue until the sun begins to set, when the sky grows noticeably redder. How does scattering cause this phenomenon?

My investigation: Careers in Energy Assignment: My Research Plan

Ball 1, with a mass of 150 g and traveling at 15 m/s, collides head on with ball 2, which has a mass of 350 g and is initially at rest.

At what angle should the roadway on a curve with a 50m radius be banked to allow cars to negotiate the curve at 12 m/s even if the road way is icy (and the frictional force is zero)

What particle can be stopped by skin

What was significant about the atomic theory that democrituis proposed?

What is the mechanical advantage of a pulley?

What kind of movement does the heat within the core and mantle directly generate?

Explain why Newton's first law of motion can be difficult to observe in moving objects?