3 protons should be your answer
The formula of the kinetic energy is:

where m is a mass of the object, v is speed of the object at the moment of time. So we have:

The answer is
2000 Joules.
Average speed = (total distance covered) / (time to cover the distance)
Total distance covered = (9.5m + 3.5m + 15m) = 28 meters
Time to cover the distance = 43 seconds
Average speed = (28 meters) / (43 seconds)
Average speed = 0.65 meters/second
Answer:
Part a)

Part b)

Part c)

Explanation:
As we know that 5000 kg African elephant requires 70,000 Cal for basic needs per day
so we will have


so we have energy required per kg


Part a)
now we know that per kg the energy required will be same
so we have mass of the human is 68 kg
so energy required per day is given as


Part b)
Resting power is the rate of energy in Joule required per sec
so it is given as


Part c)
resting power given in the book is

so this is less than the power given


Answer:
1.85c
Explanation:
a photon moves at c, the electron is moving at 0.85c, and since they are moving in opposing directions, the relative speed would be 1.85c