Kinetic Energy = (1/2) (mass) (speed)
First runner: KE = (1/2) (45kg) (49 m/s) = 1,102.5 Joules
Second runner: KE = (1/2) (93kg) (9 m/s) = 418.5 Joules
The <em>first runner </em><em>has 163</em>% more kinetic energy than the second runner has.
Here As we can see the figure that the end of the rope is pulled by some force F
Now as we can see that Piano is connected by a pulley which is passing over the pulley so effectively net force on the piano upwards will be 2F as it is connected by 2 ropes by the pulley
Now for constant velocity of the piano we will say

since velocity is constant so acceleration must be ZERO
so here we have

as we know here that
mg = 1000 N
so we will have


so here force must be 500 N
I think this is TRUE. Ph is calculating the acidic acids in water. And you need to know the concentration of hydronium ions. Hope this helped !