Abackpack has a mass of 8 kg. it is lifted and given 54.9 j of gravitational potential energy. how high is it lifted? acceleration due to gravity is g = 9.8 m/s2.

The potential energy for a lifted object is U = m*a*h

where m is the mass, h is the height and a is the acceleration.

in our problem the mass is m = 8kg, the height is the thing we want to find, a is the gravitational acceleration, 9.8 m/s^2 and U = 54.9j

then our problem is:

54.9j = h*9.8*8 kg*m/s^2

then h = 54.9/(9.8*8) = 0.7m

Then the backpack is lifted 0.7 meters.

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

this means that the temperature of both substances will be equal