calculate the kinetic energy of a car of mass 750kg moving with a velocity of 54 km h. Find the new kinetic energy of the car if a passenger of mass 50 kg sits in the car.
Answers
Answer:
Velocity of the car = 54*5/18 m/s = 15 m/s
Now,
Kinetic energy = 1/2 mv^2
= 1/2 * 750*225 = 84375 Joules.
Now ,if additional increase of 50 kilograms is done as the man enters, the total mass of the system becomes 800 kilograms
Still, the kinetic energy of the car remains the same as both the mass and the velocity of the car remain the same.
Just that the kinetic energy of the complete system will now become higher.
It'll be
= 1/2* 800* (15)^2 = 400*225 = 90000 Joules.
If the question demands that the man enters the car as it's moving from some or the other way from the top, then by momentum conservation in the horizontal direction calculate the new velocity of the system and then the kinetic energy of both the car and the system will be changed and can be further numerically calculated.
Hope this helps you !