Explain why only very large stars can form black holes

The hammer of an electric bell strikes 1440 times in a minute and does a work of 0.2 J per strike. what is the power of hammer in S. I. system?

A copper bar of length h and electric resistance r slides with negligible friction on metal rails that have negligible electric resistance (see figure below. the rails are connected on the right with a wire of negligible electric resistance

State the degree: rst+r^2s^2+r^3s^2

A particle of charge + 13 µC and mass 3.57 10-5 kg is released from rest in a region where there is a constant electric field of + 495 N/C. What is the displacement of the particle after a time of 1.50 10-2 s?

During a race such as a marathon, the skeletal muscle cells in your legs use a lot of energy to continually contract and power your muscles. What organelle is most likely abundant in skeletal muscle cells?

8. A force of 80 pounds on a rope is used to pull a box up a ramp inclined at 100 from the horizontal. The rope forms an angle of 330 with the horizontal. How much work is done pulling the box 25 feet along the ramp?

A raindrop has a mass of 5.4 * 10-7 kg and is falling near the surface of the earth. Calculate the magnitude of the gravitational force exerted (a) on the raindrop by the earth and (b) on the earth by the raindrop.

As an astronaut travels towards Earth, her weight A. decreases because gravity decreases. B. decreases because her mass decreases. C. increases because gravity increases. D. remains the same because her mass remains the same.

Lightning often strikes water. a. True b. False

How much work must be done on a 10 kg snowboard to increase its speed from 4 m/s to 6 m/s?