A child holds a ball of mass m a distance h above the ground. Check all of the following statements that describe potential energy correctly in this case. (Assume potential energy is zero when the ball is on the ground.)
1. The ball alone has potential energy mgh.
2. The system of the earth and the ball together have potential energy mgh

In which of the following cases is work being done on an object? question 2 options: pushing against a locked door carrying a box down a corridor pulling a trailer up a hill suspending a heavy weight with a strong

Acarpenter builds an exterior house wall with a layer of wood 2.9 cm thick on the outside and a layer of styrofoam insulation 2.3 cm thick on the inside wall surface. the wood has k=0.080w/(m⋅k), and the styrofoam has k= 0.010 w/(m⋅k). the interior surface temperature is 19.0 ∘c , and the exterior surface temperature is -15.0 ∘c . a.)what is the temperature at the plane where the wood meets the styrofoam? celsius b.)what is the rate of heat flow per square meter through this wall? /m^2

Asmall 12.00g plastic ball is suspended by a string in a uniform, horizontal electric field with a magnitude of 10^3 n/c. if the ball is in equilibrium when the string makes a 30 ° angle with the vertical, what is the net charge on the ball?