Work Calculator
Work from force, distance and the angle between them.
Why the cosine
W = F × d × cos(θ)
Only the force component along the motion does work. Pulling a sled with a rope at 45° wastes cos(45°) ≈ 29% of your effort lifting instead of pulling. At 90° no work is done at all, which is why carrying a suitcase down a flat street, exhausting as it is, does zero mechanical work on the suitcase.
Feel for the numbers
3,000 J (150 N over 20 m) is less than one kilocalorie: a single peanut fuels a lot of sled pulling. Human muscles are simply inefficient converters, burning several times the mechanical output as heat.