Contact and non contact forces- NEW GCSE PHYSICS SPEC

I think the resources are really useful. I was also looking for the answers of the worksheet. Are they available?<br /> <br /> Thank you very much and a wonderful job done :)

There are some misconceptions in here, like the understanding of Newton's 3rd law with the trolley question. It's not clear since an overall force would mean the trolley is accelerating/decelerating (Newton's 2nd law). <br /> Also due to Newton's 3rd law the force that the trolley exert on each other is equal and opposite. There wouldn't be an overall force because of this. This is similar to the example of if you shot a bullet through a tissue - the force the bullet exerts on the tissue is the same that the tissue exerts on the bullet.<br /> Would be better to have just the one trolley and say the pushing force is 50N - and there is a friction force, from a polished floor surface, of 50N. The trolley is therefore travelling at constant speed. If the trolley was moved onto a carpet, the friction force increases. If the friction force is now 70N, and you still push the trolley with 50N of force - the overall force is 20N in the opposite direction of pushing. HOWEVER this only causes a deceleration - as in the trolley slows down.<br /> <br /> It's really key that Newton's laws aren't misunderstood.