The sun heats the Earth through the process of radiation.
Hope this helps,
Davinia.
The speed of the rock at 20 m is 34.3 m/s
Explanation:
We can solve this problem by using the law of conservation of energy: the mechanical energy of the rock, sum of its potential energy + its kinetic energy) must be conserved in absence of air resistance. So we can write:
where
:
is the initial potential energy
is the initial kinetic energy
is the final potential energy
is the final kinetic energy
The equation can also be rewritten as follows:
where:
m = 100 kg is the mass of the rock
is the acceleration of gravity
is the initial height
u = 0 is the initial speed (the rock starts at rest)
is the final height of the rock
v is the final speed when h = 20 m
And solving for v, we find:

Learn more about kinetic energy and potential energy here:
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Answer:
The correct option is;
B. 8 m, because he has to apply less force over a greater distance
Explanation:
In the given question, in order for the student to lift the boxes onto the tuck with less amount of force, he applies the principle of Mechanical Advantage
The mechanical advantage is given by the measure by which a force is amplified through the use of a tool
Given that the work done = The force × The distance, we have
F₁ × d₁ = F₂ × d₂, which gives;
d₁/d₂ = F₂/F₁
Where;
F₁ = The input force
F₂ = The output force
d₁ = The input distance
d₂ = The output distance
The Mechanical advantage, MA = d₁/d₂ = F₂/F₁
Therefore, when the input distance is increased the input force will be reduced for a given output force
Answer:
4.9 m/s
Explanation:
Since the motion of the ball is a uniformly accelerated motion (constant acceleration), we can solve the problem by using the following suvat equation:

where
v is the final velocity
u is the initial velocity
a is the acceleration
s is the distance covered
For the ball in this problem,
u = 0 (it starts from rest)
is the acceleration
s = 3 m is the distance covered
Solving for v,
