Question

A car burns 3 x 10^5 J of fuel (chemical energy) per

second. It has 1.3 x 10^5 J of kinetic energy and gains
0.7 x 10^5 J of gravitational potential energy as it goes
up a slope. How much energy transfers away from
the car through thermal energy transfer? Assume that
acceleration due to gravity g = 10 m/s².

Answer 1

The total energy of the car is the sum of its kinetic energy, potential energy, and chemical energy:

Total energy = Kinetic energy + Potential energy + Chemical energy

Total energy = 1.3 x 10^5 J + 0.7 x 10^5 J + 3 x 10^5 J

Total energy = 5 x 10^5 J

Since energy cannot be created or destroyed, the total energy of the car must remain constant. Any energy that is not accounted for in the car's kinetic, potential, or chemical energy must be transferred away from the car through thermal energy transfer. Therefore, the thermal energy transfer can be calculated as:

Thermal energy transfer = Total energy - (Kinetic energy + Potential energy + Chemical energy)

Thermal energy transfer = 5 x 10^5 J - (1.3 x 10^5 J + 0.7 x 10^5 J + 3 x 10^5 J)

Thermal energy transfer = 0.9 x 10^5 J

Therefore, 0.9 x 10^5 J of energy transfers away from the car through thermal energy transfer.