6th grade · Science · Unit 6 of 9
Work, Energy & Efficiency
Force, distance and wasted energy
What your child practices
Using the scientific terms force, displacement, work, energy and efficiency, calculating work as force times displacement, finding efficiency, and how friction and design affect the energy lost from machines.
California Content Standards learning standard: MS-PS3-5 · when an object's kinetic energy changes, energy is transferred to or from it, as in work
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
A machine does 150 J of work moving a load 6 m. What force did it apply, in N?
answer boxN
25 N
Hint: Force = work ÷ displacement.
Question 2
A streamlined shape helps a cyclist go farther on the same energy because it…
- adds friction
- adds weight
- removes gravity
- reduces air resistance
reduces air resistance
Hint: Less drag means less energy is wasted pushing through air.
Question 3
The force on a cart doubles and the distance stays the same. What happens to the work?
- It becomes zero.
- It halves.
- It doubles.
- It stays the same.
It doubles.
Hint: Work is proportional to the force.
Question 4
In science, work is done when a force…
- is read in a book
- is applied but nothing moves
- is thought about
- moves an object through a distance
moves an object through a distance
Hint: Work needs both a force and movement.
Question 5
A force of 20 N does 160 J of work. How far, in m, did the object move?
answer boxm
8 m
Hint: Displacement = work ÷ force.
Question 6
A force of 10 N moves a crate 7 m in the direction of the force. How much work is done, in J?
answer boxJ
70 J
Hint: Work = force × displacement.