The driver of a speeding truck slams on the brakes and skids to a stop through a distance d. On another trial, the initial speed of the truck is half as large. What now will be the truck’s skidding distance? (a) (b) (c) d (d) d/2 (e) d/4
The stopping distance of the truck for half the initial speed is , and Option (e) is correct.
The stopping distance for the first case is .
The initial speed in the second case is
The work-energy theorem is used to find the stopping distance for half the initial speed in the second case.
Apply the work-energy theorem for the truck in the first case.
Here, m is the mass of the truck, u is the initial speed of the truck, and F is the braking force.
Apply the work-energy theorem for the truck in the second case.
Divide equation (2) by equation (1) to find the stopping distance of the truck in the second case.
The stopping distance of the truck for half the initial speed is .
Therefore, the stopping distance of the truck for half the initial speed is , and Option (e) is correct.
Question: If an object is in equilibrium, which of the following statements is not true? (a) The speed of the object remains constant. (b) The acceleration of the object is zero. (c) The net force acting on the object is zero. (d) The object must be at rest. (e) There are at least two forces acting on the object.
Question: A crate of weight is pushed by a force on a horizontal floor as shown in Figure P5.89. The coefficient of static friction is , and is directed at angle below the horizontal. (a) Show that the minimum value of that will move the crate is given by
(b) Find the condition on in terms of for which motion of the crate is impossible for any value of .
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