Fundamentals 14

Question 1

What is the equation relating the force of friction to the coefficient of friction?

Answer 1

Ff=(mu)Fn

Question 2

An object attached to a horizontal spring oscillates in simple harmonic motion. What is the equation for the magnitude of the net force on the object? And describe the direction of that net force.

Answer 2

F=kx, where the direction is always toward the equilibrium position

Question 3

An object on a platform scale has mass 3 kg. Describe a situation in which the normal force on the object is greater than 30 N.

Answer 3

landing on the scale, acceleration of elevator is opposite g

Question 4

What is the equation for the potential energy of an object-spring system?

Answer 4

Us=(1/2)kx^2

Question 5

A steady force of 5 N acts on a 3 kg object over a distance of 6 m. How much work is done by the steady force on the object?

Answer 5

W=fx; 30 Joules

Question 6

Write the equation for rotational kinetic energy.

Answer 6

KEr = (1/2)Iw^2

Question 7

Write the equation for rotational inertia of a point object.

Answer 7

I = mvr

Question 8

What are the units of power?

Answer 8

watt or joules/sec

Question 9

A person attached to a parachute falls through the air at constant speed. What is the Newton’s third law force pair to the person’s weight?

Answer 9

force of person on earth (opposite of earth on person)

Question 10

An object rotates clockwise and slows down. Is the net torque on the object clockwise, counterclockwise, or zero?

Answer 10

counterclockwise, as there is rotational acceleration in the direction opposite of motion