Answer:

1/2 mv²

k. e=4j

v=2m/s

4=1/2*m2²

8=4m

m=2

Given that:

KE = 4 J

v = 2 m/s

KE = 1/2 mv^2

4 = 1/2 × m × 2 × 2

4 = 2m

m = 2

hope it's help you......