Question

Problem 1- A 4 kg puck can slide with negligible friction over a horizontal surface, taken as the xy plane.
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The puck has a velocity of 3i m / s at one instant ti = 0 . Eight seconds later, its velocity is to be
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8i + 10 j m / s . Find the magnitude and direction of the net force acting on the puck.

Answer 1

the later speed is 10.

So, the acceleration is 10m/s /8s = 1.25 m/s^2

F = ma 3*1.25 = 5N