Homework 7.2 Solutions

Homework 7.2 solutions

1 / A point mass of weight 6.2N is acted on by a horizontal force of 3.8N.
(a) / Calculate the resultant of these two forces.
magnitude: _____ N direction: _____ ° anticlockwise to horizontal
(b) / Determine the magnitude and direction of a third force acting on the object for it to be in equilibrium.
magnitude: _____ N direction: _____ ° anticlockwise to horizontal
2 / A small object of weight 5.4N is at rest on a rough slope, which is at an angle of 30° to the horizontal.
(a) / Sketch a diagram and show all three forces acting on the object.
(b) i / Calculate the frictional force on the object.
(b)ii / Calculate the support force from the slope on the object.
3 / An archer pulled a bowstring back until the two halves of the string are at 140° to each other (see diagram below). The force is needed to hold the string in this position was 95N.
(a) / Calculate the tension in each part of the bowstring in this position.
(b) / Calculate the resultant force on an arrow at the instant the bowstring is released.
4 / An elastic string is stretched horizontally between two fixed points 0.80m apart. An object of weight 4.0N is suspended from the midpoint of the string, causing the midpoint to drop a distance of 0.12m.
(a) / Calculate the angle of each part of the string to the vertical.
(b) / Calculate the tension in each part of the string.

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