Answer: a) It will take more time to return to the point from which it was released
Explanation: To determine how long it takes for the ball to return to the point of release and considering it is a free fall system, we can use the given formula:
, where:
d is the distance the ball go through;
v₀ is the initial velocity, which is this case is 0 because he releases the ball;
a is acceleration due to gravity;
t is the time necessary for the fall;
Suppose <em>h</em> is the height from where the ball was dropped.
On Earth:
h=0.t + 
h = 5t²
= 
On the other planet:
h = 0.t + 
h = 15.t²
= 
Comparing the 2 planets:
=
or 
Comparing the two planets, on the massive planet, it will take more time to fall the height than on Earth. In consequence, it will take more time to return to the initial point, when it was released.
Answer:
h = 40.37 m
Explanation:
We will apply the law of conservation of energy to the skier in this case, as follows:

where,
m = mass of skier = 77 kg
g = acceleration due to gravity = 9.81 m/s²
vf = final speed = 30 m/s
vi = initial speed = 2 m/s
W_friction = Work done by friction and air resistance = 4000 J
Therefore,
![(77\ kg)(9.81\ m/s^2)h = \frac{1}{2}(77\ kg)[(30\ m/s)^2-(2\ m/s)^2] - 4000\ J\\\\h = \frac{34496\ J - 4000\ J}{755.37\ N}\\\\](https://tex.z-dn.net/?f=%2877%5C%20kg%29%289.81%5C%20m%2Fs%5E2%29h%20%3D%20%5Cfrac%7B1%7D%7B2%7D%2877%5C%20kg%29%5B%2830%5C%20m%2Fs%29%5E2-%282%5C%20m%2Fs%29%5E2%5D%20-%204000%5C%20J%5C%5C%5C%5Ch%20%3D%20%5Cfrac%7B34496%5C%20J%20-%204000%5C%20J%7D%7B755.37%5C%20N%7D%5C%5C%5C%5C)
<u>h = 40.37 m</u>
Answer:
Scientists believe it is the best explanation because it is built on data and observations. The majority of the scientific community voted on this theory over other possible explanations. It is the best explanation because it supports the beliefs and opinions of most scientists.
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