A 60.0 kg runner is moving at 6.00 m/s and speeds up to 9.00 m/s. The runner’s change in kinetic energy is 1,350 J. How much work was done? –2,430 J –1,350 J 1,350 J 2,430 J

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s

overcharge is the right answer system