Answer: The correct explanation is 2.
Explanation: The warm air is less dense (it expands) and thus it is lighter than the cold air so it will rise up to the floor. Therefore, when you place the heater on the floor it will warm the cold air which would then rise and be replaced by more cold air which would again get warm and rise and so on until the room is heated. This means that the correct explanation is 2.
On the other hand, if you put the heater at the ceiling, it will warm the cold air near the ceiling which would stay up there (it is lighter than the cold air under it). This means that the only way for the heat to spread from this ceiling level warm air to the lower levels is via conduction which is slow.
Gravity.: Gravity is the force that acts at a right angle to the path of an orbiting object.
Answer:
60000 J
Explanation:
Assuming the force is applied parallel to the displacement of the elephant, the work done to move it across the floor is

where
F = 2000 N is the force applied
d = 30 m is the displacement of the elephant
Substituting the numbers into the formula, we find

Answer:
Initial Velocity is 4 m/s
Explanation:
What is acceleration?
It is the change in velocity with respect to time, or the rate of change of velocity.
We can write this as:

Where
a is the acceleration
v is velocity
t is time
is "change in"
For this problem , we are given
a = 1.2
t = 10
Putting into formula, we get:

So, the change in velocity is 12 m/s
The change in velocity can also be written as:

It is given Final Velocity = 16, so we put it into formula and find Initial Velocity. Shown Below:

hence,
Initial Velocity is 4 m/s