Find the amount of energy transfered to a box that you are pushing if it required 720 watts of power to push the box for 6 seconds
an object can only accelerate when the forces acting on it are unbalanced.
when that happens
-- the object's speed increases, or
-- its speed decreases, or
-- the direction of its motion changes.
b. a car of mass 2000 kg with speed 7 m/s
the kinetic energy of an object is given by:
where m is the mass of the object and v is its speed.
from the formula, we see that the larger the mass and the speed of the object, the larger its kinetic energy. among the choices given, we see that the car with largest mass and largest speed is car b, which has a mass of 2000 kg and speed of 7 m/s. its kinetic energy is:
we can verify that the other cars have smaller kinetic energy. in fact:
- car a:
- car c:
- car d:
so, car b is the one which has most kinetic energy.