a body of mass 20kg initially at rest is subjected to a force of 40N for 1sec calculate the change in kinetic energy showing the solution​

Change in KE is 40 J

Explanation:

Recall that the impulse exerted on an object equal the change of momentum of the object (ΔP), which in time is defined as the product of the force exerted on it times the time the force was acting:

Change in momentum is:   ΔP = F * Δt

In our case,

ΔP = 40 N * 1 sec = 40 N s

Since the object was initially at rest, its initial momentum was zero, and the final momentum should then be 40 N s.

So, the initial KE was 0, and the final (KEf) can be calculated using:

KEf = 1 /(2 m) Pf^2 = 1 / (40) 40^2 = 40 J

So, the change in kinetic energy is:

KEf - KEi = 40 J - 0 j = 40 J

i think they are all correct

explanation:

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the answer is neither ball has a charge.

because if they were both positively charged, they will repel each other.

if they were positively and negatively charged, they will seek.