When a person bends an arm a different muscle is used to bring it back to the original position. why can't the same muscle be used to both bend and unbend the arm?

A flashlight beam is directed at a swimming pool in the dark at an angle of 46° with respect to the normal to the surface of the water. What is the angle of refraction of the beam in the water? (The refractive index for water is 1.33.)

Which statement describes the kinetic energy and total mechanical energy of a block as it is pulled at constant speed up an incline? (1) Kinetic energy decreases and total mechanical energy increases.

The pressure in the liquids decreases with depth. true or false

What is true about the size of terrestrial Planets

A gun shoots a bullet with a velocity of 500. M/s. the gun is aimed horizontally and fired from a height of 1.50 m. How far does the bullet travel?

Race car drivers must slow down as they make turns on the track. This is best explained by the law of inertia. Which statement best describes inertia for the car going around a turn? A) A body in motion stays in motion at the same speed.

What is is the ratio of the distance over which the force is applied to the distance over which the load is moved

What factor can increase the potential energy of an object? A Decrease in speed B Decrease in density C Increase in temperature D Increase in height from the ground?

Microwave ovens emit microwave energy with a wavelength of 12.3 cm. What is the energy of exactly one photon of this microwave radiation?

When light bounces off a surface, which component will be reflected more - the component that is parallel to the surface, or the component that is perpendicular to the surface, and why?