A block of mass m = 1.80 kg is pushed a distance d = 5.00 m along a frictionless

Question

A block of mass m = 1.80 kg is pushed a distance d = 5.00 m along a frictionless, horizontal table by a constant applied force of magnitude F = 16.0 N directed at an angle = 23.0° below the horizontal as shown in the figure below.

(a) Determine the work done on the block by the applied force. J

(b) Determine the work done on the block by the normal force exerted by the table. J

(c) Determine the work done on the block by the gravitational force. J

(d) Determine the work done by the net force on the block. J

Explanation / Answer

a) Work = Force*distance*cos(angle between them) The angle in this case is 23.0°. You can consider the terms in this order

Work = Force*cos23.0°*distance in which case the Force*cos20.0° is the component of the force that is parallel with the surface of the table.

W = 16* cos23 * 5 = 73.64 J

b) This would be zero. The block's motion is at 90.0° to the normal force. Cos90 = 0.

c) This would be zero. The block's motion is at 90.0° to gravity. Cos90 = 0.

d) The net force is F*cos23.0°. The vertical component of F and the weight and the normal force all cancel out. So the answer here is the same as answer a.

W = 73.64 J

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