Review Questions for Dynamics (Forces) Unit:

Equations you will be given:

                                                           

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1.     Three toy sleds are attached to each other by a string. They are being pulled on frictionless ice with force of 9.0 N.The last sled has a mass of 1.0 kg, the middle has a mass of 2.0 kg and the front has a mass of 3.0 kg.  Find

          a) the acceleration of the sleds    b) the tension in the sting connecting the last sled and the middle sled.

2.  A 50. kg person stands in an elevator.
        a) How much does he weigh when the elevator is at rest?
        b) How much does it aopear he weighs when the elevator accelerates UP at 2.0 m/s2? (Hint: Fn is how much he   appears to weigh so solve for Fn)
        c) How much does it appear he weighs when the elevator accelerates DOWN at 2.0 m/s2?

3. A 2.0 kg sled is being pulled by a force of 10. N [E} and a force of 20. N [S45E] on frictionless ice. What is the net force and the net acceleration?

4. A  surface has mK = 0.40. A force of 45 N is applied to a box of mass 40 kg. Determine the acceleration of the box.

5. Your friend is pulling you while you are on a skateboard (on a frictionless floor). You start from rest and travel a distance of 2.0m in 2.0s. Your mass is 55 kg. Determine the net force your friend is pulling you with.

6.  A puck of mass 0.5 kg slides across some rough ice and comes to a stop.  Its initial speed was 5.0 m/s and it stopped in a distance of 20. m. Determine the puck's acceleration and the coefficient of friction of the ice.