A.. in case of any problems that may occur you would know what company to call
Answer:

Explanation:
It is given that,
Depth of Death valley is 85 m below sea level, 
The summit of nearby Mt. Whitney has an elevation of 4420 m, 
Mass of the hiker, m = 65 kg
We need to find the change in potential energy. It is given by :



or

So, the change in potential energy of the hiker is
. Hence, this is the required solution.
The correct answer for the question that is being presented above is this one: "B.pushing against a car without moving it." According to the scientific definition, pushing against a car without moving it is not an example of work. Lifting a book off a desk and <span>pulling socks out of the drye are samples of work.</span>
Answer:
Explanation:
Given that,
Mass of sledge hammer;
Mh =2.26 kg
Hammer speed;
Vh = 64.4 m/s
The expression fot the kinetic energy of the hammer is,
K.E(hammer) = ½Mh•Vh²
K.E(hammer) = ½ × 2.26 × 64.4²
K.E ( hammer) = 4686.52 J
If one forth of the kinetic energy is converted into internal energy, then
ΔU = ¼ × K.E(hammer)
∆U = ¼ × 4686.52
∆U = 1171.63 J
Thus, the increase in total internal energy will be 1171.63 J.
The momentum goes to the wall