PUSH or PULL

[Lounge Lizard]

silly me i forgot to google first

That horse walks backwards.

[TrueBlueTerrier]

Been off ill with a bad back. Seen 2 doctors and 2 physios and all of them have said to push the trolley. When you reach your arm behind you to pull a trolley you actualy twist your back slightly, hence putting an uneven strain on it.

That makes sense, but could someone with a better understanding of physics than me confirm that there's more resistance with and therefore more effort involved in pushing rather than pulling a trolley ?
Mothers push rather than pull prams but they're not too heavy and they like to keep an eye on their little darlings.

If you push or pull exactly horizontal then the friction force should be the same. In practice however, you often push at a downward angle. Only part of your applied force is horizontal. The other part is vertically down. This adds to the object's weight and the Normal force increases and then so will friction, as it is proportional to the normal force. When you pull, you frequently pull at an upward angle. The vertical part of your applied force is up which subtracts from the object's weight, resulting in a smaller Normal force and a smaller frictional force.

[Lounge Lizard]

Been off ill with a bad back. Seen 2 doctors and 2 physios and all of them have said to push the trolley. When you reach your arm behind you to pull a trolley you actualy twist your back slightly, hence putting an uneven strain on it.

That makes sense, but could someone with a better understanding of physics than me confirm that there's more resistance with and therefore more effort involved in pushing rather than pulling a trolley ?
Mothers push rather than pull prams but they're not too heavy and they like to keep an eye on their little darlings.

If you push or pull exactly horizontal then the friction force should be the same. In practice however, you often push at a downward angle. Only part of your applied force is horizontal. The other part is vertically down. This adds to the object's weight and the Normal force increases and then so will friction, as it is proportional to the normal force. When you pull, you frequently pull at an upward angle. The vertical part of your applied force is up which subtracts from the object's weight, resulting in a smaller Normal force and a smaller frictional force.

Thanks, That's precisely what I did NOT learn, but should have, in physics lessons at secondary school.