Gravity is the force that pulls you down.
(This is kind of a duh! question ... How do we know
which way is "down" ? We feel gravity, and we call
that the "down" direction.)
Magnetic force holds things to fridge doors.
Contact forces need to touch something in order to
exert their force.
Example: Gravity is NOT a contact force.
I don't know about "rubbing things away".
This might be a description of friction, but if so,
it's not a good one.
Buoyant force is what keeps floating things floating.
Air resistance slows things down when they move in air.
Answer: 500 Watts
Explanation:
Power 
is the speed with which work 
is done. Its unit is Watts (), being 
.
Power is mathematically expressed as:
(1)
Where 
is the time during which work is performed.
On the other hand, the Work done by a Force 
refers to the release of potential energy from a body that is moved by the application of that force to overcome a resistance along a path. It is a scalar magnitude, and its unit in the International System of Units is the Joule (like energy). Therefore, 1 Joule is the work done by a force of 1 Newton when moving an object, in the direction of the force, along 1 meter (
).
When the applied force is constant and the direction of the force and the direction of the movement are parallel, the equation to calculate it is:
(2)
In this case, we have the following data:
So, let's calculate the work done by Peter and then find how much power is involved:
From (2):
(3)
(4)
Substituting (4) in (1):
(5)
Finally:
Answer:
e) None of these is true
Explanation:
Given that
Temperature = 0 K
We know that relationship between kelvin and Farenheit scale
Now by putting the values
So F= - 459.67°F
So we can say that 0 K is equal to - 459.67°F.
So the our option e is correct.
-- The truck begins the scenario moving at 6 m/s.
-- After increasing its speed at the rate of 2 m/s² for 12 seconds,
it has gained (2 x 12) = 24 m/s of speed, and it's then moving
at 30 m/s.
-- The truck's average speed during the 12 seconds is (1/2) (6 + 30) = 18 m/s
-- Traveling at an average speed of 18 m/s for 12 seconds,
the truck travels
(18 m/s) x (12 sec) = 216 meters
