An 80 000-kg airliner is flying at 900 km/h at a height of 10.0 km.What is its total energy (kinetic + potential)if the total was 0 when the airliner was at rest on the ground?
A)250 MJ
B)478 MJ
C)773 MJ
D)10 300 MJ

Question

Quizplus · Accepted Answer

To calculate the total energy of the airliner, we need to add its kinetic energy and potential energy.

Kinetic Energy: 
KE = (1/2)mv^2
KE = (1/2)(80,000 kg)(250 m/s)^2 (convert 900 km/h to m/s) 
KE = 2 x 10^9 J

Potential Energy: 
PE = mgh 
PE = (80,000 kg)(9.81 m/s^2)(10,000 m) (convert 10 km to m) 
PE = 7.85 x 10^9 J

Total Energy: 
TE = KE + PE 
TE = 2 x 10^9 J + 7.85 x 10^9 J 
TE = 9.85 x 10^9 J

Therefore, the answer is D) 10,300 MJ.

An 80 000-Kg Airliner Is Flying at 900 Km/h at a Height