Physics
it is estimated that 1.0 kg of body fat will provide
3.8 × 107 j of energy. a 60-kg mountain climber decides
to climb a mountain 4000 m high.
(a) how much work does the climber do against
gravity in climbing to the top of the mountain?
the answer for this is 2.4x10^6
(b) if the body’s efficiency in converting energy stored as
fat to mechanical energy is 25%, determine the
amount of fat the climber will use up in providing the
energy required to work against the force of gravity.
the answer is 0.25kg
i got a) but i don't understand how to do b)

Aman does 500 j of work pushing a car a distance of 2 m. how much force does he apply? assume there is no friction. a. 250 n b. 1000 n c. 125 n d. 500 n

A1kg cart slams into a stationary 1kg cart at 2 m/s. the carts stick together and move forward at a speed of 1 m/sl. determine whether kinetic energy was conserved in the collision. use the law of conservation of energy to explain the collision

Mass (kg) force (n) 5 25 10 50 15 75 20 100 a student was trying to find the relationship between mass and force. he placed four different masses on a table and pulled them using a spring scale. the table shows the different masses used in the experiment and the force required to pull each mass. the student concluded that more force was required to pull heavier objects. what comment would you make regarding his conclusion? a) no clear relation can be observed between mass and force from the data. b) there is a direct proportion between the mass and force listed in the table. c) gravity should have been taken into account while performing the experiment. d) there is an inverse proportion between the mass and force listed in the table.