Answer:
the faster an object moves the more kinetic it has. the more mass an object has, the more kinetic energy it has.
Efficiency = Power Output / Power Input
Power Input = Rate of Energy input = 44.4 MJ/kg * 5 kg/h
= 222 MJ/h
But 1 hour = 3600seconds
222 MJ/h = 222 MJ/3600s = 0.061667 MW J/s = Watts
Power input = 0.061667 MW = 61 667 W
From Efficiency = Power Output / Power Input
28% = Power Output / 61667
Power Output = 0.28 * 61667
Power Output = 17266.76 W
Power Output ≈ 17 267 W
Rate of heat rejection = Power Input - Power Output
= 61667 - 17267 = 44400 W
Rate of heat rejection = 44 400W.
I’m pretty sure it’s lean mass but let another guy answer you before you use mine
(a) 154.5 N
Let's divide the motion of the sprinter in two parts:
- In the first part, he starts with velocity u = 0 and accelerates with constant acceleration
for a total time
During this part of the motion, he covers a distance equal to
, until he finally reaches a velocity of
. We can use the following suvat equation:

which reduces to
(1)
since u = 0.
- In the second part, he continues with constant speed
, covering a distance of
in a time
. This part of the motion is a uniform motion, so we can use the equation
(2)
We also know that the total time is 10.0 s, so

Therefore substituting into the 2nd equation

From eq.(1) we find
(3)
And substituting into (2)

Solving for t,

So from (3) we find the acceleration in the first phase:
And so the average force exerted on the sprinter is

b) 14.5 m/s
The speed of the sprinter remains constant during the last 55 m of motion, so we can just use the suvat equation

where we have
u = 0
is the acceleration
is the time of the first part
Solving the equation,
