Question 1

If the weight of a car doubles, its kinetic energy ________.

Accepted Answer

The kinetic energy of an object is given by the formula KE = 1/2 mv^2, where m is the mass and v is the velocity. If the weight (mass) of the car doubles, the kinetic energy doubles as well, assuming the velocity remains constant.

Question 2

Weight transfer during braking is caused by ________.

Accepted Answer

Weight transfer during braking is primarily caused by inertia. When a vehicle decelerates, the inertia causes the weight of the vehicle to shift towards the front, increasing the load on the front wheels and reducing it on the rear wheels.

Question 3

A typical hanging brake pedal is a ________.

Accepted Answer

A typical hanging brake pedal is a second-class lever because the load (brake force) is between the fulcrum (pivot point) and the effort (force applied by the foot).

Question 4

The coefficient of friction is found by ________.

Accepted Answer

The coefficient of friction is calculated by dividing the tensile force (frictional force) by the normal force (weight force).

Question 5

What factors determine the friction coefficient?

Accepted Answer

The friction coefficient is primarily determined by the materials in contact (friction material) and the roughness or smoothness of the surfaces (surface finish), not by the surface area or thickness.

Question 6

A 3000 pound vehicle is calculated to have a kinetic energy of 90,000 ft-lb at 28 mph. If the speed of the vehicle remains the same and the weight is doubled to 6000 pounds, what will happen to the calculated kinetic energy?

Accepted Answer

Kinetic energy is directly proportional to the mass of an object when the velocity remains constant. Therefore, doubling the weight of the vehicle from 3000 pounds to 6000 pounds will double its kinetic energy from 90,000 ft-lb to 180,000 ft-lb.

Question 7

It takes 50 pounds of force to move a 100 pound block of wood across the floor. The coefficient of friction is ________.

Accepted Answer

The coefficient of friction is calculated as the force required to move an object divided by the normal force (which, in this case, is the weight of the object). Here, it's 50 pounds of force to move a 100 pound block, so the coefficient of friction is 50/100 = 0.5.

Quiz 93: Braking System Principles