My physics teacher gave us a huge packet with some review problems that we should know how to do for the test. There are 3 that I have no clue how to do.(adsbygoogle = window.adsbygoogle || []).push({});

1.) A morbidly obese man weighing 500 newtons stands 2.5 meters from the inner edge of a nail supporting a wooden platform. The wooden platform he stands on weighs 200 newtons, and is a total distance of 6 meters long. The platform is supported at the end by a steel cable (in blue) making a 45˚ angle above the horizontal.

Part A: Draw a free-body diagram representing this situation.

Part B: Find the tension T in the string (indicated by the blue arrow).

Part C: Find the force P that the nail exerts on the wooden platform (indicated by the green arrow). Give the magnitude of the force, along with the unknown angle theta.

I can do part B but that's about it. How do you do part a and c???

2.) A ball of mass M is attached to a string of length L and is swung in a vertical circle just above the ground. The tension T in the string at the top of its swing is 2g. The ball barely clears the ground at its minimum point.

Part A: Find the velocity of the ball at the top of its orbital. Express your answer only in terms of M, g, and L.

Part B: Find the tension T in the string at the bottom of its orbital. Express your answer only in terms of M, g, and L.

Part C: Find the centripetal acceleration of the ball at the top of its orbital. Express your answer only in terms of M, g, and L.

I don't know what to do. I know a= (v^2)/r but I don't have a. Is this the correct formula for this problem?

3.) A large block of mass 1.5 kg is attached to a spring, which is connected over a massless, frictionless pulley. Both of them are hung on opposite sides of the pulley, as illustrated in the diagram above. The spring has a force constant of 500 N/m, and is initially at its equilibrium position. The block is also released from its equilibrium position. After release, the block falls 3 centimeters before it hits the ground. Find the velocity v, in meters per second, just before the instant that the block strikes the ground.

I don't know what to do.

Any help would help. Thanks

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# Homework Help: Physics review

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