A block of mass lies on a horizontal table the

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A block of mass lies on a horizontal table. The coefficient of static friction between the block and the table is . The coefficient of kinetic friction is , with . Part A If the block is at rest (and the only forces acting on the block are the force due to gravity and the normal force from the table), what is the magnitude of the force due to friction? Hint 1. Consider the type of friction at rest What type of friction is acting in this case?
Correct Part B Suppose you want to move the block, but you want to push it with the least force possible to get it moving. With what force must you be pushing the block just before the block begins to move? Express the magnitude of in terms of some or all the variables , , and , as well as the acceleration due to gravity . Hint 1. Consider the type of friction to start movement What type of friction is acting in this case?
3/21/2016 Homework 6
29/31 Correct Part D Suppose you push horizontally with precisely enough force to make the block start to move, and you continue to apply the same amount of force even after it starts moving. Find the acceleration of the block after it begins to move. Express your answer in terms of some or all of the variables , , and , as well as the acceleration due to gravity . Hint 1. Calculate applied force What is the magnitude of the force that you are applying to make the block move?
Correct Part C Suppose you push horizontally with half the force needed to just make the block move. What is the magnitude of the friction force? Express your answer in terms of some or all of the variables , , and , as well as the acceleration due to gravity . Hint 1. What level of force is required? In this situation, the force of static friction prevents the object from moving. Therefore, the magnitude of the static friction force must equal the magnitude of the net horizontal applied force acting on the object, up to a certain maximum value. In this case, , where is the coefficient of static friction and is the normal force that the surface exerts on the object.
3/21/2016 Homework 6 Express your answer in terms of some or all of the variables , , and , as well as the acceleration due to gravity .
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