A force of 0.5 N acts on a body weighing 10 kg for two seconds. Find the final kinetic energy of the body if the initial kinetic energy is zero.
F = 0.5 Newton – the force acting on the body;
m = 10 kilograms – body weight;
t = 2 seconds – the period of time during which the force acted on the body.
It is required to determine E (Joule) – the final kinetic energy of the body.
Since, according to the condition of the problem, the initial kinetic energy of the body is equal to zero, it means that its initial velocity was also equal to zero. Then, we find the acceleration of the body:
a = F / m = 0.5 / 10 = 0.05 m / s ^ 2.
Then its final speed will be equal to:
v = a * t = 0.05 * 2 = 0.1 m / s.
Knowing the speed, we find the kinetic energy:
E = m * v ^ 2/2 = 10 * 0.1 ^ 2/2 = 5 * 0.1 ^ 2 = 5 * 0.01 = 0.05 Joules.
Answer: the kinetic energy of the body will be equal to 0.05 Joules.
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