A 42.9 kg wagon is towed up a hill inclined at 19.7◦ with respect to the horizontal. The
tow rope is parallel to the incline and exerts
a force of 165 N on the wagon. Assume that
the wagon starts from rest at the bottom of
the hill, and disregard friction.
The acceleration of gravity is 9.81 m/s
2
.
How fast is the wagon going after moving
22.5 m up the hill?
Answer in units of m/s.

Two resistors r1 and r2 may be connected either in series or parallel across an ideal battery with emf ε. we desire the rate of energy dissipation of the parallel combination to be 8.75 times that of the series combination. if r1 = 105 ω, what are the (a) smaller and (b) larger of the two values of r2 that result in that dissipation rate?

Consider the growth of a 20-nm-diameter silicon nanowire onto a silicon wafer. the temperature of the wafer surface is maintained at 2400 k. assume the thermal conductivity of the silicon nanowire is 20 wm-1k-1 and all its surfaces including the tip are subjected to convection heat transfer with the coefficient h = 1×105 wm-2k-1 and t∞ = 8000 k. when the nanowire grows to l = 300 nm, what is the temperature of the nanowire tip (t (x =

How are positive ions different from neutral atoms