A car driver uses a screw jack to lift a $1000\text{ kg}$ car while changing a flat tire. Why can a single…
A car driver uses a screw jack to lift a $1000\text{ kg}$ car while changing a flat tire. Why can a single human lift such a heavy car using a screw jack?
The screw jack multiplies the distance turned into a much larger vertical movement.
The long spiral thread provides a large mechanical advantage by spreading effort over a long distance.
The screw jack reduces the mass of the car temporarily.
The threads convert magnetic energy of the car frame into upward lift.
Solution
The continuous spiral thread of a screw jack functions as an inclined plane. Turning the thread over a large rotational distance lifts the heavy load a small vertical distance, greatly multiplying effort force.