The efficiency of the light bulb is 8.9%. This means that only 8.9% of the power of the lightbulb becomes useful power, and it corresponds to:
The rest of the power instead is wasted as heat, and this amount of power wasted is given by the difference between the total power and the useful power:
So, the power wasted as heat is 13.66 W.
If you wish, you could choose i to be in the same direction as the motion and j in perpendicular direction (upwards).
The two speeds could be expressed as vectors. The speed of the boat is merely
. The speed of the climbing man, using the boat as reference, is more complicated. It is
. Calculate the sums of the two and the speed itself.
The internal energy of the
system is characterized by the equation U = Q + W where U is the internal
energy, Q is the heat and W is work. You are given 2,380 J of energy to do work
as 12,900 J of heat so add up. The internal energy is 15,280J.