So i believe is exercise:)
Answer:
The acceleration of the crate is
.
Explanation:
Given that,
Force, F = 750 N
Mass of the crate, m = 250 kg
The coefficient of friction is 0.12.
We need to find the acceleration of the crate. The net force acting on the crate is given by :

f is frictional force, 

So, the acceleration of the crate is
. Hence, this is the required solution.
Answer:

Explanation:
The expression which represent the first diffraction minima by a circular aperture is given by
--------eqn 1
The angle through which the first minima is diffracted is given by
---------eqn 2
As
is very small so we can write 
So from eqn 1 and eqn 2 we can write
--------eqn 3
Here
is the position of first maxima D is the distance of screen from the circular aperture d is the diameter of aperture
It is given that diameter of circular aperture is 14.7 cm so 
Now putting all these value in eqn 3


Answer:
Explanation:
Given that:
Charge Q = 10400 C
current I = 0.530 mA
From our previous knowledge, we know that charge Q can be expressed as:
Q = I×t
where
I = current and t = time
∴
replacing our values
10400 = (0.530×10⁻³) t
t = 10400/(0.530×10⁻³)
t = 19622641.51 seconds
However, the required flow of electrons per seconds can be calculated by using the formula:
number of electrons/second = current (I)/ charge on electron
= (0.530×10⁻³)/(1.6×10⁻¹⁹)
= 3.3125×10¹⁵ electrons