3 Work and Energy Online Quiz Questions

A force acts perpendicular to an object's displacement. The work done by that force is zero.

A constant $12\,\text{N}$ force pulls an object through $5\,\text{m}$ at an angle of $60^\circ$ to its displacement. How much work does the force do?

Changing the chosen zero-height reference for gravitational potential energy does not change predictions based on changes in potential energy.

An object moves at $3\,\text{m/s}$ while a $20\,\text{N}$ force acts at $60^\circ$ to its velocity. What instantaneous power does the force deliver?

A machine does $600\,\text{J}$ of work in $4\,\text{s}$. What is its average power? Enter the numerical value in watts.

Select all statements that correctly describe a conservative force.

A one-dimensional force is $F_x(x)=3x\,\text{N}$ for positions from $x=0$ to $x=4\,\text{m}$. How much work does it do over that interval?

A $2\,\text{kg}$ object is raised from $1\,\text{m}$ to $4\,\text{m}$ above the chosen reference level. Use $g=9.8\,\text{m/s}^2$. What is its change in gravitational potential energy? Enter the numerical value in joules.

Two objects are released from rest from the same height above the ground. If air resistance is neglected, the heavier object has a greater speed just before reaching the ground.

Select all statements consistent with energy accounting when friction does work.

A $2\,\text{kg}$ object speeds up from $3\,\text{m/s}$ to $5\,\text{m/s}$. What is the net work done on it?

A system has initial mechanical energy $40\,\text{J}$, and friction does $-12\,\text{J}$ of work. Find the final mechanical energy and explain what the negative work implies about energy transformation and total energy conservation.

Which statement describes a conservative force?

A constant $12\,\text{N}$ force pulls an object through a displacement of $4\,\text{m}$, at an angle of $60^\circ$ to the displacement. How much work does the force do?

An ideal spring has spring constant $100\,\text{N/m}$ and is stretched $0.20\,\text{m}$ from its relaxed length. What potential energy is stored in the spring?

A one-dimensional force varies with position as $F_x(x)=(3\,\text{N/m})x$. What work does it do as an object moves from $x=0$ to $x=2\,\text{m}$?

A $2\,\text{kg}$ object is raised vertically by $3\,\text{m}$ near Earth's surface, where $g=9.8\,\text{m/s}^2$. What is the change in its gravitational potential energy? Enter the numerical value in joules.

A $4\,\text{kg}$ cart moves at $3\,\text{m/s}$. What is its translational kinetic energy? Enter the value in joules.