# Chinese Family Value

Topics: Rotation, Force, Torque Pages: 1 (425 words) Published: July 10, 2012
College Physics 1 - Homework L due Wednesday 11/23/10 1. A toy gun uses a spring to project a 5.3 g soft rubber sphere horizontally. The spring constant is 8.0 N/m, the barrel of the gun is 15 cm long, and a constant frictional force of 0.032 N exists between barrel and projectile. Prior to firing, the spring is compressed 5.0 cm, leaving the sphere at the back of the gun’s barrel. With what speed does the projectile leave the barrel when fired? 2. State whether each of the following interactions is explosive, elastic, inelastic, or perfectly inelastic. Give supporting calculations and/or explanations. a) Activity 7.1 Question 3, b) Activity 7.1 Question 4, and c) Activity 7.1 Question 5. 3. A turntable is rotating at 45 rpm when the power is turned off. If it rotates through 45 rad as it uniformly comes to rest, determine its angular acceleration. 4. Consider a carousel 32 feet in diameter. This carousel takes 11 s to accelerate from rest to its operating speed of 3.25 rev/min. During this time, find a) its angular acceleration and b) the number of revolutions made. Now, consider a horse situated half way between the edge and the center of this carousel. Determine its c) maximum speed, d) maximum centripetal acceleration, and e) tangential acceleration. 5. Explain why you extend your arms to help keep your balance. 6. A 0.125 kg meter stick is rotating (as shown to the right) in a horizontal plane about an axis through its center at 3.45 rad/s. a) At one of its ends, find its b) speed and c) centripetal acceleration. If this stick comes to rest in 4.27 s, find d) its angular acceleration and e) the net torque acting on it. 7. Tidal forces apply a braking force on the Earth as the water flows against the floor of the ocean basins. The result is that the rotation period of the Earth is constantly slowing down. Scientists estimate that a day used to be 18 hours long about 900 million years ago. a) Find the Earth’s angular speed 900 million years ago in SI units. b)...