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Unit 2 physics paper gcse 2014

I don't understand how to answer the question 3 (a) (iii) on terms of forces and how velocity changes? Can anyone help me?

Reply 1

uberteknik

Original post by TigWood

I don't understand how to answer the question 3 (a) (iii) on terms of forces and how velocity changes? Can anyone help me?

Hello and welcome to TSR. :smile:

If you want an answer, you will first need to scan and attach a copy of the FULL question.

You should also make an attempt at answering the question as well as stating why you are in difficulty. Only then people will people understand how best to help and guide you to the correct answer.

You will find many people only too willing to help out but you must put the effort in too!

Thanks. :smile:

Reply 2

username1567177

Original post by TigWood

I don't understand how to answer the question 3 (a) (iii) on terms of forces and how velocity changes? Can anyone help me?

If you tried to put the question onto the forum it would help, duh! :mad:

Reply 3

TigWood

These are the two pages on the question.

Original post by TigWood

I don't understand how to answer the question 3 (a) (iii) on terms of forces and how velocity changes? Can anyone help me?

This is a detailed description. If you are able to distil and précis for the examination, so much the better.

The bicycle is propelled forwards by the constant force provided by the cyclist. This force is transmitted to the road wheels in contact with the road surface where friction creates an equal and opposite reaction to propel the bicycle forwards.

Because the bicycle starts from a standstill the air resistance, caused by friction with cyclists body and the air and acting in opposition to the propulsion force, is also negligible. All of the constant propulsion force provided by the cyclist translates into maximum acceleration as shown by the steep gradient at the start of the velocity/time curve.

As the bicycle increases velocity, the air resistance also increases and more propulsion force is needed to continue accelerating the bicycle.

Increasing velocity is therefore accompanied by a reduction in acceleration because the propulsion force provided by the cyclist is constant and an increasing proportion is needed to overcome air resistance as shown by a reduction in the gradient of the velocity/time graph.

Eventually, the velocity reaches a maximum when all of the propulsion force reaches equilibrium balance with the air resistance and the bicycle achieves a constant velocity with no further acceleration.