Answer:0.27
Explanation:
Given
One worker Pushes with force 
other Pulls it with a rope of rope 
mass of crate 
both forces are horizontal and crate slides with a constant speed
Both forces are in the same direction so Friction will oppose the forces and will be equal in magnitude of sum of two forces because crate is moving with constant speed i.e. net force is zero on it

where
is the friction force



where
is the coefficient of static friction



Answer:
When there is nearsightedness or myopia
Explanation:
As, in myopia the image is formed in front of the retina.
Which makes things looking at things near very easy, but looking at far away things very difficult.
So concave lens makes things look bigger, so therefore, it is used during myopia, to make things look bigger when they are far away
Answer:
30643 J
Explanation:
= Vacuum permeability = 
t = Time taken = 1 ns
c = Speed of light = 
= Maximum electric field strength = 
A = Area = 
Magnitude of magnetic field is given by

Intensity is given by

Power, intensity and time have the relation

The energy it delivers is 30643 J
Answer:
2156 J
Explanation:
From the question,
Work done = Combined mass of the bucket and water×height×gravity.
W = (M+m)hg............................. Equation 1
Where M = mass of water, m = mass of the bucket, h = height, g = acceleration due to gravity.
Given: M = 20 kg, m = 2 kg, h = 10 m
Constant: g = 9.8 m/s²
Substitute these value into equation 1
W = (20+2)×10×9.8
W = 22×98
W = 2156 J