1) There were two blocks, X and Y with masses 4kg and 1kg respectively. A steady force of 12.3N acts on block X and the block moved at a steady speed of 6m/s. If the forces between X and Y is 3.1N, find the frictional force acting on X and Y respectively.
2) Two blocks, X and Y of masses 2kg and 6kg respectively were initially at rest on a horizontal surface. A steady force of 10N acts on block X and the blocks accelerated to a speed of 6m/s in 12 seconds. If the forces between X and Y is 5N, find the frictional force acting on X and Y respectively.
3)(*) There were two blocks, X and Y with masses 5kg and 2kg respectively. A steady force of 40N acts on block X and the block accelerated to a speed of 18m/s in 4.5 seconds. If the frictional force acting on X is 10N, i) find the force that Y exerts on X.
ii) hence, find the force that X exerts on Y (hint, Newton's 3rd law)
iii) lastly, find the frictional force acting on Y.
Question 3 is significantly harder than 1) and 2). Please let me know if you found the questions easy, hard, or manageable. I'll be going through them tmrw.
When I exert a force on block X, the force does not 'extend to block Y'. Since my hand is only on X, I do NOT exert any force on Y. The reason why Y will move is because of the force X exerts on it (they are in contact), or due to the tension (in the case of the examples I've went through in class). This concept is very important, please bear it in mind!
cheers.
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