Answer:
The force is 
Explanation:
The diagram for this question is shown on the first uploaded image
From the question we are told that
The weight of the gate is 
The vertical component of F is 
From the diagram , taking moment about the pivot we have
Where 
is the weight of the gate evaluated as
=> 
=> 
=>
Choices 'C' and 'D' are both correct.
(Except in 'C', changing the temperature from 1°C to 3°C is not usually
described as 'cooling', and it's not the water's 'mass' that changes. But
water does contract in volume during that change.)
If you increase the mass m of the car, the force F will increase, while acceleration a is kept constant. Because F and m are directly proportional.
If you increase the acceleration a of the car, the force F will increase, while mass m is kept constant. Because F and a are directly proportional.
How can Newton's laws be verified experimentally; is by setting this experiment, and changing one variable while keeping the other constant, then observe the change in F.
Hope this helps.
Answer: False
Explanation:
Relative to the concept of radiations, a black body is an object capable of absorbing any form of electromagnetic radiation irrespective of its frequency or angle of incidence when incident on such object.
However, the same cannot be said about real bodies as real bodies are those which reflect all rays incident on them completely and uniformly in all directions.
One very important characteristic of black bodies is that they are ideal emmiters.
The concept of emmisivity is brought about by the existence of real bodies .
This is due to the fact that they are only able to emit radiation at a fraction of the black body energy levels.
Please note that by convention, the emmisivity of a real body is always less thaan 1.
As such they are not able to emit as much radiation as a black body at the same temperature.
