Two forces act on a puck that moves over friction less along one dimensional motion. The puck’s mass. Forces F and G are directed along the axis and have magnitudes is directed at angle and has magnitude . In each situation, what is the acceleration of the puck.

SOLUTION. The Key Idea in situation is that we can relate the to the net force acting on the puck with Newton’s second law.However because the motion is along on axis, we can simplify each situation by writing the second for x components only.

The positive answer indicates that the acceleration is in the positive direction of the x axis.

Thus the net force accelerates the puck ill the positive direction of there axis.

From the figure, we see that. Solving for the acceleration and substituting for yield

Thus, the net force accelerates the puck in the negative direction of the x axis.

CHECKPOINT 3: The figure shows overhead views of four situations in which two forces accelerate the same block across a friction less floor. Rank the situations according to the magnitudes of (a) the net force on the block and (b) the acceleration of the block, greatest first.