Answer
Mass m = 78 kg
Vertical height in each stage h = 11 m
(a).
Initial speed u = 0
Final speed v = 1.1 m / s


a = 0.055 m/s²
Work done




(b).Work done

W_b = 78× 9.8× 11

c)
Work done

Where V = final speed
= 0
v = 1.1 m / s
for deceleration a = -0.055 m/s²
now,

W_c = 545.75 × 11

Answer:
part (a). 176580 J
part (b). 197381 J
Explanation:
Given,
- Density of the chain =

- Length of the chain = L = 60 m
- Acceleration due to gravity = g = 9.81

part (a)
Let dy be the small element of the chain at a distance of 'y' from the ground.
mass of the small element of the chain = 
Work done due to the small element,

Total work done to wind the entire chain = w

part (b)
- mass of the block connected to the chain = m = 35 kg
Total work done to wind the chain = work done due to the chain + work done due to the mass

Answer:
Explanation:
We shall apply Gauss's theorem for electric flux to solve the problem . According to this theorem , total electric flux coming out of a charge q can be given by the following relation .
∫ E ds = q / ε
Here q is assumed to be enclosed in a closed surface , E is electric intensity on the surface so
∫ E ds represents total electric flux passing through the closed surface due to charge q enclosed in the surface .
This also represents total flux coming out of the charge q on all sides .
This is equal to q / ε where ε is a constant called permittivity which depends upon the medium enclosing the charge . For air , its value is 8.85 x 10⁻¹² .
If charge remains the same but radius of the sphere enclosing the charge is doubled , the flux coming out of charge will remain the same .
It is so because flux coming out of charge q is q / ε . It does not depend upon surface area enclosing the charge . It depends upon two factors
1 ) charge q and
2 ) the permittivity of medium ε around .
Answer:
The change in momentum = -20000 kg m/s.
Explanation:
Mass m = 1000 kg
speed v₁ = 20 m/s
speed v₂ = 0 m/s
We know that,
The change in momentum
ΔP = m (Δv)
ΔP = m (v₂ - v₁)
= 1000 (0 - 20)
= 1000 (-20)
= -20000 kg m/s
Thus, the change in momentum = -20000 kg m/s.
Note: negative sign indicates that the velocity is reducing when it hits the barrier.
Wood is a poor conductor and therefore a good insulator keeping heat inside