Work and Power Calculator
Calculate work with W = F·d·cos θ and power with P = W / t. Find work done by a force at an angle and the power delivered over time, in SI units.
Work (W = F·d·cos θ)
600 J
Power (P = W / t)
120 W
Work: W = F·d·cos θ in joules (J). Power: P = W / t in watts (W). Set θ = 0° when the force is along the direction of motion.
Frequently Asked Questions
What is the formula for work?
Work equals force times displacement times the cosine of the angle between them: W = F × d × cos θ. The result is in joules (J). When the force is in the direction of motion (θ = 0°), cos θ = 1 and W = F × d.
How do I calculate power from work?
Power is the rate of doing work: P = W / t, where W is work in joules and t is time in seconds. The result is in watts (W). For example, 600 J done in 5 s is 120 watts.
Why does the angle matter for work?
Only the component of the force along the direction of motion does work. The cos θ factor extracts that component. If the force is perpendicular to the motion (θ = 90°), cos θ = 0 and no work is done.
Can work be negative?
Yes. When the force opposes the motion (angle greater than 90°), cos θ is negative, so the work is negative — for example, friction doing negative work on a sliding object.
What are the units of work and power?
Work is measured in joules (J), where 1 J = 1 N·m. Power is measured in watts (W), where 1 W = 1 J/s.