How do you accelerate without changing force in this scenario?

That is a bit of a trick question.

You see, acceleration in physics is really just change in speed whether its an increase or decrease.

so, your friend is right.

to further explain...

if you think about it. when your going around a corner in a car, (with your foot on the gas  and going at a steady speed) your car will naturally decrease in speed.

now, what happens if while your turning that corner and a raccoon jumps in front of the car?

you might naturally turn the car in the car even harder to miss the raccoon, thus changing the angle of the force.

and your car will even decrease in speed more.

meaning your car accelerated to a lower speed because you changed the angle of the force.

someone please correct me if im wrong.

The question is badly worded.  Because "without changing force" means both the magnitude and direction of the force can't change.  In  that case you would have  to reduce the mass of the cart (e.g. take something from it) or reduce friction (e.g put oil under it).

I'm guessing the question actually means "without changing the magnitude of the force".

In that case there are 2 possibilities.

1) Reduce the angle to the horizontal. The produces a larger horizontal component which increases the magnitude of (horizontal) acceleration but doesn't change its direction.

2) Change the direction of the force about the vertical (I.E. to the left or right). This produces a change in direction of the cart  which counts as an acceleration; if you change it so much that the force is perpendicular to the cart's direction, this will result in circular motion.

But I would guess that the question wants option 1).



You have ot change the direction.

Changing the angle to the horizontal won't do this. The direction of the force left/right mst change. That will cause the direction to change - hence

There are a few errors in the wording of the question.
As the conditions stand the cart MAY already be accelerating.
Nothing in the question says that it isn't.
The cart MAY be moving at a constant speed.  Or the cart may be stationary due to friction.

But let us suppose that under these conditions the cart is NOT accelerating yet.
Is it stationary or is it moving?
If it is moving at constant speed at the moment then any alteration to the force will alter its motion.

However UNLESS you change the force in some manner then the cart cannot subsequently accelerate.
Changing the angle IS changing the force.

Force is a vector made of magnitude and direction.

They question MAY have meant "without changing the MAGNITUDE of the force"

But to have a question with two serious errors in it warrants an investigation.

Let us imagine that the question meant only magnitude was to be unchanged.

If the body was moving at a constant speed in any direction at all then changing the angle of the force in any way will produce some acceleration.
That acceleration may be positive, negative, or sideways.  Depending on the angle chosen.

If the body is currently at rest due to friction then there is no guarantee that anything you do will make it move.
If we lower the angle to less than 70 degrees from the horizontal we have increased the horizontal component of the force.
At the same time we have reduced the vertical component of the force which was lifting the weight slightly.
The result is that the friction will be increased.
The weight may or may not accelerate.

Both can be done

If he pulls the cart in circular motion there is no change in magnitude but only direction.

By changing the angle of the force the vertical component of the force changes.