A frog can be many different colours. It appears green under normal 'white' light because it absorbs all the other colours in the light's spectrum apart from green. It reflects the green light back and that is picked up by your eye.
If the light is red, there is no green in the spectrum of the light, only red. So, the red light will be absorbed and there is no green to be reflected back for you to see. Therefore, the frog will not look green.
The ration of output work to input work expressed as a percentage is called <u>Efficiency</u>.
Answer:
The mass of the box:
m = 60 kg
Explanation:
Given:
F = 150 N
g = 10 m/s²
_________
m - ?
Coefficient of friction wood on wood:
μ = 0.25
Friction force:
F₁ = μ*m*g
Newton's Third Law:
F = F₁
F = μ*m*g
The mass of the box:
m = F / ( μ*g) = 150 / (0.25*10) = 60 kg
