SPH4C – Friction - PBworks

SPH4C – Friction 1. A block is ... The coefficient of static friction between a 10 kg object and the floor is 0.50. ... A hockey puck has a coefficien...

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SPH4C – Friction  1. A block is sitting on a table. You push on it with a force of 1 N to the right. It doesn't move. There is _______________ friction opposing the motion and the magnitude of that force of friction must be _________ . You push with a force of 2 N to the right and it still doesn't move; the force of ______________ friction must be ________ . You continue to gradually increase the force with which you push until, when your force just exceeds 4 N, the block finally starts to move. This means the magnitude of the ______________________ friction between the block and the surface of the table is _________ . To keep the block moving at constant velocity, you have to keep pushing with a constant force of 3 N. This means the magnitude of the force of _______________ friction between the block and the surface of the table is equal to 3N. While it is moving at constant velocity, the net force on the block is _________ N. 2. In the picture below, explain why the bear fell. Use FRICTION to explain your answer.

3. How does surface roughness affect friction? 4. Discuss the relationship between the size and weight of an object and the amount of friction that is present 5. Analyze how friction can be both a positive and negative aspect in our everyday lives. Use examples to support your statements. 6. Sports such as soccer involve running, stopping, jumping, and kicking. Discuss how friction helps players.

7. Complete the table below:

Mass Force of m GravityFg (kg) (N) 30

Normal Force FN (N)

Coefficient of Static Friction µs

Force of Static Friction Ff (N)

1.0 1176

1100 0.67

4.9

 

8. The coefficient of static friction between a 10 kg object and the floor is 0.50. What is the maximum force that can be applied on the object before it starts moving?

9. A hockey puck has a coefficient of kinetic friction of μk = .10. If the puck feels a normal force (FN) of 5 N, what is the frictional force that acts on the puck?

10.Suppose a 10 N force is applied to the side of a 4.0 kg block that is sitting on a table. The block experiences a frictional force against the force that is applied.

a. b. c. d.

Draw a free body diagram for the block? What is the weight of the block (FG)? What is the normal force on the block (FN)? If the coefficient of kinetic friction is μk = .20, what is the frictional force on the block (Fk)? e. What is the net force on the block? f. What is the acceleration of the block from the net force? g. What would be the minimum value of the coefficient of static friction in order for the block to remain motionless?