CE Board Exam Randomizer

Question 1

Work and Energy Principles

1. The work done by a force is the product of the magnitude of the force and the displacement it makes in the direction of the force.

$$ W = F \times d $$

Where:
  W → work done on a body (N·m)
  F → force
  d → displacement

2. Only forces in the direction of motion do work.

3. Forces that cause the motion do positive work.

4. Forces that retard the motion (e.g., friction) do negative work.

5. Energy is the capacity to do work.

6. Potential Energy is the energy of a body due to its position above a datum line.

7. Kinetic Energy is the capability of the body to do work due to its velocity.

$$ KE = \frac{1}{2} mv^2 $$

Question 2

Work–Energy Method

The change in kinetic energy is equal to the positive work minus the negative work.

$$ \Delta KE = \text{Positive Work} \; - \; \text{Negative Work} $$

Question 3

Problem: Crate Sliding Down a Ramp

A 16-lb crate slides down a ramp as shown. If the crate is released from rest 10ft. agove the bottom of the ramp and the coefficient of friction between the crate and the ramp is 0.2, determine the speed of the crate when it reaches the bottom of the ramp.

Question 4

Problem: Biker Sliding Down a Ramp

The biker starts from rest at A and travels down the ramp. If friction and air resistance can be neglected, determine the biker's speed v_B when he reaches B. Also compute the distance, d, to where he strikes the ground at C if he makes the jump travelling horizontally at B. Neglect the biker's size. He has a mass of 70kg.