Physics Question! Why does a heavier weight pull an object faster if objects fall at the same rate?

Question

A weight is attached to a hanging end of a string, which on the other side is attached to a cart on a track. Why does the heavier weight pull the cart faster if all objects fall at the same rate?

Also, why does the string always stay taut?

Answer 1

Objects do not fall at the same rate. The heavier object is more massive and therefore has more gravity and attracts the earth more, and so accelerates faster.

But that is negligible, what you really need to know, is that the lighter weight, is usually more buoyant, and so accelerates slower.

I have never seen a string that always stays taut.

Answer 2

actually, this is only true if one side of it has resistance. in this case, the cart on a track. following the previous answer with F=m * a, the force exerted by a heavier weight exerts more force to overcome the resistance of the cart on the track which is a function of the weight of the cart and how squeaky the wheels are.

string is taut 'cos that's how the energy is transfered - across the string. if the string is dangly, it means that the cart's moving faster than the weight.

Answer 3

The heavier hang mass exerts more force - weight is force of gravity acting on a mass. If the cart's mass is the same, then the heavier mass, which exerts a greater force on the rope hence the cart, which results in the cart having a greate acceleration than with the lighter mass. By the way, the masses don't fall with the same acceleration. You can show that the acceleration of the falling masses is:

a = g* M/(M+m) where g = acceleration due to gravity, M = mass at end of rope, and m = mass of cart. Since m and g do not change, if you change M, then a changes and you can show that a is smaller for a lighter mass than for a heavier one.

Answer 4

Because the weight is connected to another object.

When a weight is dropped it is just converting its (gravitational)potential energy to kinetic.
If it is attached to the cart then some of thi potential energy is also transfered to the cart.

Answer 5

F = m * a

The heavier weight will have exert more force on the cart and its acceleration is defined as above.

Answer 6

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All objects fall with same acceleration due to gravity(g)

Weight of an object =mass x acceleration of gravity = mg.

When an object is suspended from a string, the force exerted by the object on the string is weight of the object .The weight of an object depends on its mass.

Mass of heavy object is more ,hence heavy object of more weight, exerts more force,heavy object will pull another object faster .
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