A tugboat pulls a ship along a canal with a constant 2000 N force, parallel to the motion, at a steady 3 m/s.
No single job's work total is named, and no stopwatch time: just a force and a speed. What power does the tug deliver?
A steady speed of 3 m/s means the ship covers 3 m in each second.
So in each second, the 2000 N force acts through 3 m of distance. 2000 × 3 = 6000. The tug does 6000 J of work each second: 6000 W.
F is the force in newtons; v is the steady speed in meters per second; P comes out in watts.
The same force at a greater speed transfers energy at a greater rate. At a steady 6 m/s, the same force gives 2000 × 6 = 12000, so 12000 W: double the speed, double the power.
Nothing new hides in P = Fv. It is still work per second, with the force acting through the distance the motion covers each second.
A tugboat applies a constant 2000 N force to a ship, parallel to the motion, at a steady 3 m/s. Calculate the power delivered.
Write down the values in the question:
F = 2000 N, v = 3 m/s; P = ?
Write down the equation:
P = Fv
Substitute in the values, and calculate:
P = 2000 × 3 = 6000
The tug delivers 6000 W.
A tow cable applies a constant 420 N force to a trailer moving at a steady 5 m/s, parallel to the motion. Enter the power delivered, in watts.
A tractor applies the same constant force to a loaded sled while its steady speed rises. Edda says: 'The tractor now transfers energy at a greater rate.' Is she correct?
A cable applies a constant 350 N force to a mine cart moving at a steady 8 m/s, parallel to the motion. Calculate the power delivered.
Write down the values in the question:
F = 350 N, v = 8 m/s; P = ?
Write down the equation:
P = Fv
Substitute in the values, and calculate:
P = 350 × 8 = 2800
The cable delivers 2800 W.
A truck's driving force stays a constant 900 N while its steady speed doubles from 4 m/s to 8 m/s. Enter the new power delivered, in watts.
A snow groomer's winch cable applies a constant 650 N force to a sled of equipment moving at a steady 12 m/s, parallel to the motion. Enter the power delivered, in watts.
For which situation does P = Fv give the power delivered by the force?
An electric van's motor applies a constant 540 N driving force at a steady 15 m/s on a level road. Enter the power delivered, in watts.