(a) Kinetic energy of an object is defined as the energy possessed by a body by virtue of its motion.
It is given by, K.E = 1/2 mv2
No, the kinetic energy of an object cannot be negative since both mass of the object, m and velocity of a substance, v cannot be negative.
(b) Given,
Mass of the car, m = 1200 kg , Distance covered, s = 40 m
Time taken, t = 5 s, Initial velocity, v = 0
Work done, W =?
Since, W = F × s = ma × s [ Since, F = ma ]
For calculating work done, acceleration (a) is required.
Therefore using, s = ut + 1 /2 at2
40 = 0 × t + 1 /2 a × 52
⟹ = 40×2 /25 = 3.2 m/s 2
Now, W = F × s = ma × s
= 1200 × 3.2 × 40 = 153600 J
The work needed to be done by the car engine = 153600 J
