dtmcnamara
11-19-2008, 10:18 PM
Ok so I have a huge test tomorrow and I need to review over some crap from a few months ago, and I cannot remember how to do the shit. Anyone want to help me out? I have all ov the answers I just need to figure out how to get each answer. THANKS
1. A turntable has an angular velocity of 1.4 rad/s. The coefficient of static friction between the turntable and a block placed on it is 0.20. The maximum distance from the center of the turntable that the block can be placed without sliding is approximately
2. A disc is free to rotate about an axis. A force applied at a distance d from the axis causes an angular acceleration α. What angular acceleration is produced if the same force is applied a distance 2d from the axis?
3. A disc-shaped grindstone of mass 3.0 kg and radius 8.0 cm is spinning at 600 rev/min. After the power is shut off, a man continues to sharpen his axe by holding it against the grindstone until it stops 10 s later. What is the average torque exerted by the axe on the grindstone?
4. Two kids are trying to pick some apples that are on the other side of the fence which is 1.5m high. Since there is a vicious dog on the other side, they decided to use a ladder and lean it against the fence. The ladder of negligible mass is placed at an angle of 40° to the horizontal. One kid of mass 50 kg stands at the bottom of the ladder while another kid of mass 40 kg goes up the ladder. How far up along the ladder can the lighter kid go before it tips over?
5. Large meteors can impact the earth with speeds of 80,000 km/h. If such a meteor were to impact at a point on the plane of Earth's equator, resulting in a change of Earth's angular momentum by 80 × 10^12 kg - m2/s (an insignificant change, thankfully), calculate the mass of the meteor. (The radius of Earth = 6.38 × 10^6 m.)
1. A turntable has an angular velocity of 1.4 rad/s. The coefficient of static friction between the turntable and a block placed on it is 0.20. The maximum distance from the center of the turntable that the block can be placed without sliding is approximately
2. A disc is free to rotate about an axis. A force applied at a distance d from the axis causes an angular acceleration α. What angular acceleration is produced if the same force is applied a distance 2d from the axis?
3. A disc-shaped grindstone of mass 3.0 kg and radius 8.0 cm is spinning at 600 rev/min. After the power is shut off, a man continues to sharpen his axe by holding it against the grindstone until it stops 10 s later. What is the average torque exerted by the axe on the grindstone?
4. Two kids are trying to pick some apples that are on the other side of the fence which is 1.5m high. Since there is a vicious dog on the other side, they decided to use a ladder and lean it against the fence. The ladder of negligible mass is placed at an angle of 40° to the horizontal. One kid of mass 50 kg stands at the bottom of the ladder while another kid of mass 40 kg goes up the ladder. How far up along the ladder can the lighter kid go before it tips over?
5. Large meteors can impact the earth with speeds of 80,000 km/h. If such a meteor were to impact at a point on the plane of Earth's equator, resulting in a change of Earth's angular momentum by 80 × 10^12 kg - m2/s (an insignificant change, thankfully), calculate the mass of the meteor. (The radius of Earth = 6.38 × 10^6 m.)