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.
Answer:

Explanation:
The density of an object is given by

where
m is the mass of the object
V is its volume
In this problem,
m = 42 kg
V = 22 m^3
Substituting into the equation, we find the object's density:

Answer:
(a) -1.18 m/s
(b) 0.84 m/s
Explanation:
(a)
The total linear momentum before the lumberjack begins to move is zero because all parts of the system are at res
From the law of conservation of momentum
m1v1+m2v2=0 hence m1v1=-m2v2 where m1 is mass of lumberjack, v1 is velocity of lumberjeck, m2 is mass of floating log, v2 is velocity of the floating log.
Substituting M1 for 103 Kg, V1 for 2.93 m/s, M2 for 255 Kg into the above equation we obtain
103Kg*2.93 m/s=-255Kg*V2
V2=-(103 kg*2.93 m/s)/255=-1.183490196 m/s
Hence V2=-1.18 m/s
(b)
For the second log
V(M1+M2)=m1v1 where V is the common velocity
V(103 Kg+255 Kg)=103 Kg*2.93 m/s
V=(103 Kg*2.93 m/s)/(103 Kg+255 Kg)=0.842988827 m/s
V=0.84 m/s