A man wears convex lens glasses of focal length 30cm in order to correct his eyes defect. Instead of the optimum 25cm, his dista
1 answer:
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Answer:
Explanation:
Applied force, F = 18 N
Coefficient of static friction, μs = 0.4
Coefficient of kinetic friction, μs = 0.3
θ = 27°
Let N be the normal reaction of the wall acting on the block and m be the mass of block.
Resolve the components of force F.
As the block is in the horizontal equilibrium, so
F Cos 27° = N
N = 18 Cos 27° = 16.04 N
As the block does not slide so it means that the syatic friction force acting on the block balances the downwards forces acting on the block .
The force of static friction is μs x N = 0.4 x 16.04 = 6.42 N .... (1)
The vertically downward force acting on the block is mg - F Sin 27°
= mg - 18 Sin 27° = mg - 8.172 ... (2)
Now by equating the forces from equation (1) and (2), we get
mg - 8.172 = 6.42
mg = 14.592
m x 9.8 = 14.592
m = 1.49 kg
Thus, the mass of block is 1.5 kg.
Answer:
The length at the final temperature is 11.7 cm.
Explanation:
We need to use the thermal expansion equation:
Where:
- L(0) is the initial length
- ΔT is the differential temperature, final temperature minus initial temperature (T(f)-T(0))
- ΔL is the final length minus the initial length (L(f)-L(0))
- α is the coefficient of linear expantion of steel (12.5*10⁻⁶ 1/°C)
So, we have:
Therefore, the length at the final temperature is 11.7 cm.
I hope it helps you!