Explanation:
<h2>law of conservation of mass</h2>
The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.
Answer:
part (a) 
part (b) N = 79.61 rev
part (c) 
Explanation:
Given,
- Initial speed of the wheel =

- total time taken = t = 20.0 sec
part (a)
Let
be the angular acceleration of the wheel.
Wheel is finally at the rest. Hence the final angular speed of the wheel is 0.

part (b)
Let
be the total angular displacement of the wheel from initial position till the rest.

We know, 1 revolution =
rad
Let N be the number of revolution covered by the wheel.

Hence the 79.61 revolution is covered by the wheel in the 20 sec.
part (c)
Given,
- Mass of the pole = m = 4 kg
- Length of the pole = L = 2.5 m
- Angle of the pole with the horizontal axis =

Now the center of mass of the pole = 
Weight component of the pole perpendicular to the center of mass = 

Answer:296.76 N
Explanation:
Given
mass of box 
Let
be the Tension in left side and
be the Tension in the right side
From diagram


and

![T_2\left [ \tan 80\cdot \cos 65+\sin 65\right ]=100\cdot g](https://tex.z-dn.net/?f=T_2%5Cleft%20%5B%20%5Ctan%2080%5Ccdot%20%5Ccos%2065%2B%5Csin%2065%5Cright%20%5D%3D100%5Ccdot%20g)
![T_2=\frac{100\cdot g}{\left [ \tan 80\cdot \cos 65+\sin 65\right ]}](https://tex.z-dn.net/?f=T_2%3D%5Cfrac%7B100%5Ccdot%20g%7D%7B%5Cleft%20%5B%20%5Ctan%2080%5Ccdot%20%5Ccos%2065%2B%5Csin%2065%5Cright%20%5D%7D)

Mechanical advantage is defined as

MA = 4
now we will have

as we need to pull up a box of weight 200 N
now by above formula we can find how much force it requires to pull up the box



so it requires 50 N force to pull the weight of 200 N
Answer:
density = 0.0933 kg/m
speed = 27.581 m/s
Explanation:
given data
length L = 4.5 m
mass m = 0.42 kg
force F = 71 N
to find out
mass density and speed
solution
we find linear mass density
linear mass density = mass / length
put here all value
density = 0.42 / 4.5
density = 0.0933 kg/m
and
speed of wave
speed = √(F/density)
speed = √(0.42/0.933)
speed = 27.581 m/s