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1. A trailer tire turns at 72.0 rpm and has a radius of 15.0 cm. What is the lin

ID: 1704282 • Letter: 1

Question

1. A trailer tire turns at 72.0 rpm and has a radius of 15.0 cm. What is the linear speed of a point on the outside of the tire?

2. A model helicopter pulls into a tight circular curve of radius 30.0 m. The 300 g helicopter is traveling at 90.0 km/h. What is the centripetal force that is acting on the helicopter?

3. A mechanical lift raises a 325 kg automobile 2.00 m for servicing. How much work was done by the lift?

4. A winch capable of pulling 250 lb must pull a 2800 lb load up a ramp of height 5.5 ft. Find the length of the shortest ramp for this job.

Explanation / Answer

1 ) Number of turns is = 72.0 rpm

                                        = 7.53 rad /s

linear speed v = r

                        = 7.53 rad /s * 15.0 *10^-2 m

                        = 1.12 m/s

2 ) radius of the circular curve is r = 30.0 m

             mass of the helicopter is m = 300 g

          speed is v = 90 km / h

                            = 25.02 m/ s

     F = mv^2 / r

         = 300 * 10^-3 kg * ( 25.02 m/s )^2 / 30.0 m

          = 6.26 N

3 ) mass of the lif t is m = 325 kg

         distance d = 2.00m

     Work done is W = F * d

                                = 325 kg * 2.00m

                                = 650 J