Why is it more difficult to do a sit up with your hands behind your head than when your arms are stretched out in front of you?

Consider a uniformly wound solenoid having N=210 turns, length l=0.18 m, and cross-sectional area A = 4.00 cm2. Assume l is much longer than the radius of the windings and the core of the solenoid is air. (A) Calculate the inductance of the solenoid.

140 students sit in an auditorium listening to a physics lecture. Because they are thinking hard, each is using 125 W of metabolic power, slightly more than they would use at rest. An air conditioner with a COP of 5.

Current is the movement of negative charges called protons. A. True B. False

Fuel cells A) require recharging B) emit carbon dioxide C) rely on combustion to produce energy D) all of these E) none of these

Say you want to make a sling by swinging a mass M of 1.9 kg in a horizontal circle of radius 0.042 m, using a string of length 0.042 m. You wish the mass to have a kinetic energy of 15.0 Joules when released.

When viewing a piece of art that is behind glass, one often is affected by the light that is reflected off the front of the glass (called glare), which can make it difficult to see the art clearly.

force used to lift a 25kg mass to a height of 24m in 5 sec does 2120J of work. Calculate the power.

Which statement is true about the atom? A: it contains positive electrons, uncharged protons and negative protons. B: it contains uncharged neutrons, positive electrons and negative protons.

Steel objects can become temporary magnets because they are mainly composed of which element?

How long does it takes the sun to rotate the earth?