Work, Energy and Power

Topics in this chapter

• Work and Work-Energy Applications
• Momentum, Collisions, and Restitution
• Potential Energy and Equilibrium
• Power, Pumps, and Fluid Flow
• Springs, Friction, and Energy Loss

Cheat sheet

Practice questions

1. Question 1Q-9E029B

   A block of mass 2 kg is pulled up a smooth inclined plane of inclination $30^\circ$ with a constant velocity of $2\text{ m/s}$ for a displacement of $4\text{ m}$ along the plane. The work done by the gravitational force on the block is (take $g = 10\text{ m/s}^2$):

   1. A.-40 J
   2. B.+40 J
   3. C.-80 J
   4. D.0 J
   See the answer and solution
2. Question 2Q-9FE978

   The potential energy of a particle of mass $1\text{ kg}$ moving along the x-axis is given by $U(x) = \frac{x^2}{2} - x$. The equilibrium position of the particle is at:

   1. A.x = 0
   2. B.x = 1 m
   3. C.x = -1 m
   4. D.x = 2 m
   See the answer and solution
3. Question 3Q-1F91FC

   A particle moves under the influence of a force $\vec{F} = (2x\hat{i} + 3y^2\hat{j})\text{ N}$. The work done by this force in moving the particle from the origin $(0,0)$ to the point $(2,3)\text{ m}$ is:

   1. A.25 J
   2. B.31 J
   3. C.35 J
   4. D.38 J
   See the answer and solution
4. Question 4Q-B86413

   A pump is required to lift $600\text{ kg}$ of water per minute from a well $25\text{ m}$ deep and eject it with a speed of $50\text{ m/s}$. The power of the pump is (take $g = 10\text{ m/s}^2$):

   1. A.15 kW
   2. B.25 kW
   3. C.37.5 kW
   4. D.50 kW
   See the answer and solution
5. Question 5Q-66BC3F

   A bullet of mass $20\text{ g}$ moving with a velocity of $300\text{ m/s}$ penetrates a wooden block and comes to rest after traversing a distance of $5\text{ cm}$. The average resistance offered by the block is:

   1. A.9000 N
   2. B.18000 N
   3. C.36000 N
   4. D.4500 N
   See the answer and solution