The gravitational potential energy U is defined as the product of mass m, the acceleration of gravity g and the height of object h.

We do not have the mass of the hiker. But we know that its W weight is:

Where

So:
.
So:

J
The hiker has gained 30,000 J of energy
The minimum speed that the second swimmer must have in order to catch up with the first swimmer by the end of the pool is; <u><em>4.04 m/s</em></u>
We are given the following facts;
- Both swimmers swim the same distance of 50 m for a leg of the relay race.
- Swimmer 1 swims at constant speed of 3.9 m/s.
- Swimmer 1 has a 0.450 second head start.
Formula for time taken is;
time = distance/speed
Time taken by swimmer 1 for one leg;
t₁ = 50/3.9
t₁ = 12.82 s
Since swimmer 1 has a head start of 0.45 s, then time that swimmer 2 must use in order to catch up is;
t₂ = 12.82 -0.45
t₂ = 12.37 s
Thus, speed of swimmer 2;
v = 50/12.37
v = 4.04 m/s
Read more about distance, speed and time at; brainly.com/question/24571540
Answer:
one sister, one half-brother, and three cousins.
Explanation:
Kin selection theory also called inclusive fitness theory describes the self-sacrificial behaviour of organism, animal or individual to ensure survival of closely related family at the detriment of the individual's survival in order to preserve genetic fitness or survival and reproductive success of such individual. Therefore saving one sister, one half-brother, and three cousins will preserve the genetic lineage and reproductive success of the genome of interest