What are the forces on two charges of +0.90 C and +5.0 C, respectively, if they are separated by a distance of 2.0 m?

What are similarities and differences of reflection, refraction, diffraction and absorption?

Lacie kicks a football from ground level at a velocity of 13.9 m/s and at an angle of 25.0° to the ground. how long will the ball be in the air before it lands? how far will the football travel before it lands?

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