2300 Joules is used to lift a wheelbarrow through 4 meters up an inclined plane into a container.
Why does the man use more joules (3500 J) to push the wheelbarrow?
4 answers
primarily friction loss, bearings heat up on axle where wheelbarrow wheel turns.
Okay , but if a block and tackle was used to lift an object why does it use less energy than actually pushing that object up?
It does? Not in my shipyard :) Block and tackle tends to have higher frictional losses than a wheelbarrow.
All methods do the same amount of "useful" work. That is the weight times 4 meters up. With your simple machines, wheels up ramps, blocks and tackles, you reduce the Force necessary. However you increase the distance through which the force must act (ramp length over height, length of line pulled through your blocks) and the work done is the force times the distance.
All methods do the same amount of "useful" work. That is the weight times 4 meters up. With your simple machines, wheels up ramps, blocks and tackles, you reduce the Force necessary. However you increase the distance through which the force must act (ramp length over height, length of line pulled through your blocks) and the work done is the force times the distance.
By the way, I am assuming that either way the man goes up into the container. If not then he has to move his own mass up, not only the wheelbarrow.
1 answer