18.3: More Examples
- Page ID
- 63267
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Consider a penguin sitting on a ramp, as shown in the figure on the left. The ramp makes an angle of 15\(^\circ\) with respect to the floor, the mass of the penguin is 45 kg, and the coefficient of static friction between the penguin and the ramp is 0.20.
- In the figure on the left, will the penguin slide down the ramp or not?
- Now I tie a rope to the penguin, as shown in the figure on the right. This rope goes over a frictionless, massless pulley. How hard must I pull on the rope before the penguin just starts to move?
Two children are going to race their sleds across a frozen pond. They run towards the pond and jump onto the sleds, and race for a point 10 m away from their starting point. The first child has a mass of 40 kg, and his sled has a coefficient of friction of 0.023. The second child is less massive (35 kg), but her sled has a larger coefficient of friction, 0.035.
- Which child will win the race, assuming the only forces acting on them are gravity and the contact force between the ice and sleds?
- When whoever wins reaches the finish line, how far behind them is the other?
- What is each of their speeds at the end of the race?