A simple model of the hydrogen atom suggests that the electron orbits the proton. What is the

force that keeps the electron in orbit?

A. Electrostatic

B. Gravitational

C. Strong nuclear

D. Centripetal

A ray of light is incident on a plane mirror at an angle of 40 degrees with the mirror surface. What will be the angle of reflection? a) 40 degrees b) 50 degrees c) 90 degrees d) 150 degrees

Which statement is true about physical changes and chemical changes? A. Chemical changes are not observable. B. Chemical changes always produce new substances. C. Physical changes can change physical and chemical properties. D.

Which of the following parts of an online newspaper is least likely to demonstrate an author's bias? a. movie reviews b. travel blog c. economic predictions in the financial section d. the box scores for yesterday's sporting events

What is the voltage of a circuit if the current is 6.2 A and the resistance is 18 ohms?

Polarization can be observed for all types of waves. for light waves. for short wavelengths. only at night.

According to Newton's law of universal gravitation, which statement is true? A. Lighter objects experience a higher acceleration than heavier objects. B. Falling objects accelerate as they approach the ground. C.

Thermal radiation is defined as what?

What are the similarities between p waves S waves and surface waves

How is sound energy produced A. Vibrating objects B. objects being heated C. Temperature differences D. Stationary objects

A 36.9-kg crate rests on a horizontal floor, and a 64.9-kg person is standing on the crate. Determine the magnitude of the normal force that (a) the floor exerts on the crate and (b) the crate exerts on the person.