Why is it easier to put something in a trolley than pull it than just dragging it on the floor?

Question

Other reasons than Friction force please.

Answer 1

It's the DIFFERENCE BETWEEN friction forces. Rolling friction is much less than sliding friction.

Answer 2

As a physics teacher, any answer that does not involve the word friction is wrong.

Here is the correct answer: there is a force called friction which is defined as "a natural force that resists motion." In a way, yes air resistance is a type of friction but rarely referred to as such. The friction force is equal to the coefficient of friction multiplied by its weight (if there are any physics graduates here, I recognize that it is not 100% correct, but I am ignoring the small exception to the rule). For this reason a piano is much harder to push then a book (it weighs more). There are two types of coefficients of friction, static friction and kinetic friction. Static friction is the amount that it takes to get something moving and kinetic friction is the amount to keep it moving. Static friction is always stronger then kinetic friction. That is why it is hard to push a stalled car to move but once it gets going it is easier to keep moving. The coefficient of rolling friction is ALWAYS lower then static friction.

Okay, this answer is a bluff but it is in fact incorrect. (my best attempt of being a smart alec).

All forces exhibit a pressure on the ground which is resisted of course by the normal force. Pressure is defined as force over an area. Since the area of contact of a trolley is much smaller then the area under it by just dragging it, the resistive force is much less and therefore it is easier to pull.

There ya go!

Answer 3

Actually this is sort of interesting. Assume that you have something on wheels, ans something on little wedge-shaped legs. The wheels and the wedges both present the same contact area with the floor and let's assume they're made of the same stuff, the mass of the whole shebang is the same too.

Then the coefficients of friction between the wheels and the floor, and the wedges and the floor, must naively be the same. So the answer is not just "friction." Perhaps one important difference is that the wheels are instantaneously rotating about their point of contact with the floor. That is, the very base of the wheel is always stationary relative to the point of contact on the floor (assuming there is no skidding).

Answer 4

The wheels of the trolly provide much less friction than does the dragging. Less friction equates to less work necessary to move the load.

Answer 5

There are no reasons other than friction... unless the wheels are wonky...

Answer 6

Boils down to pounds per square inch.

Answer 7

because of the wheels