Bathroom scale push-o-war Situation 1 : two people push on each other

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Bathroom scale push-o-war Situation 1 : two people push on each other - PowerPoint PPT Presentation

Bathroom scale push-o-war Situation 1 : two people push on each other

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Presentation Transcript

1. You and your friend are putting new shingles on a roof pitched at 25o. You’re sitting at the top of the roof when your friend, who is at the edge of the roof directly below you, 5.0 m away, asks for the box of nails. Rather than carry the 2.5 kg box of nails you decide to give the box a push and have it slide down to him. If the coefficient of friction between the box and the roof is 0.55, with what speed should you push the box to have it gently come to rest right at the edge of the roof?

2. Bathroom scale push-o-war Situation 1: two people push on each other Situation 2: one person pushes while the other just resists Situation 3: one person pushes the other at a constant speed Situation 4: one person accelerates the other

3. Two blocks are stacked on one another. The top block is tied to the wall while the other is pulled out from underneath it with a force of 20.0 N. The coefficient of kinetic friction between all surfaces is µk=0.34. What’s the tension in the string tied to the wall? What’s the acceleration of the bottom block?

4. QUIZ (TO TURN IN) Two blocks are connected by a rope and pulley and released from rest. The block on the left is 0.25 kg and the orange marker in the background is 12.0 cm long. Use a dynamics worksheet for your work. Draw free-body diagrams for each block. Write out Newton’s second law for each block. Measure the blocks’ acceleration. Find the mass of the block on the right.

5. A house painter uses the chair and pulley arrangement shown to lift himself up the side of a house. The painter’s mass is 70 kg and the chair’s mass is 10 kg. With what force must he pull down on the rope in order to accelerate upwards at 0.20 m/s2?

6. The sled dog is dragging both sleds A and B across the snow. The coefficient of friction between the sleds and the snow is µk=0.10. If the tension in rope 1 is 150 N, what is the tension in rope 2?