Question

if the mass of an object 10 kg ,moves from rest and covers a distance of 10m in 2 second . find the workdone of the object​

Answer 1

ANSWER

$s = ut + \frac{1}{2} a {t}^{2} \\ u = 0 \: \: \: \: \: \: \: (given) \\ s = \frac{1}{2} a {t}^{2} \\ (s = 10m) \\( t = 2sec ) \\ 10 = \frac{1}{2} \times a \times {2}^{2} \\ \frac{20}{4} = acceleration \\ \\ acceleration = 5m {sec}^{ - 2} \\ \\ mass = 10kg \\ \\ force = mass \times acceleration \\ force = 5 \times 10 \\ force = 50 \: newton \\ \\ work \: done \: = force \times displacement \\ \\ work \: done = 50 \times 10 = 500 \: joules$

Answer 2

Answer: 500 Joules

Explanation: The known variables are:

i) Mass of the body(m)= 10kg

ii) Initial speed(u)= 0(since the body starts from rest)

iii) Distance moved(d)= 10m

iv) Time taken(t)= 2s

By definition, the work done by net external force is

W=Fd, where d is the component of displacement in the direction of force

Further, F=ma [From Newton's Second Law]

⇒W=mda

Clearly, 'a' is an unknown variable and needs to be calculated. From the known variables, it is apparent that we can use Newton's Second Equation to calculate the unknown acceleration

d= ut + 0.5at^2

Since u=0,

d=0.5at^2

⇒a= 2d/t^2

Substituting this value back in our expression for W, we get

W= 2m(d^2)/t^2

Plugging in the numerical values, we obtain our final answer.

W= (2)(10)(100)/(4) = 500 J