Answer:
19.68 × 10⁻³ m
Explanation:
Given;
Original Length, L₁ = 41.0 m
Temperature Change, ΔT = 40.0°C
Thermal Linear expansion of steel is given to be, ∝
= 12 × 10⁻⁶ /°C
Generally, Linear expansivity is expressed as;
∝ = ΔL / L₁ΔT
Where
∝ is the Linear expansivity
ΔL is the change in length, L₂ - L₁
L₂ is the final length
L₁ is the original length
ΔT is the change in temperature θ₂ - θ₁ (Final Temperature - Initial Temperature)
From equation of linear expansivity
ΔL = ∝
L₁ΔT
ΔL = 12 × 10⁻⁶ /°C × 41.0 m × 40.0 °C
ΔL = 19.68 × 10⁻³ m
ΔL = 19.68 mm
Answer:
A) d = 11.8m
B) d = 4.293 m
Explanation:
A) We are told that the angle of incidence;θ_i = 70°.
Now, if refraction doesn't occur, the angle of the light continues to be 70° in the water relative to the normal. Thus;
tan 70° = d/4.3m
Where d is the distance from point B at which the laser beam would strike the lakebottom.
So,d = 4.3*tan70
d = 11.8m
B) Since the light is moving from air (n1=1.00) to water (n2=1.33), we can use Snell's law to find the angle of refraction(θ_r)
So,
n1*sinθ_i = n2*sinθ_r
Thus; sinθ_r = (n1*sinθ_i)/n2
sinθ_r = (1 * sin70)/1.33
sinθ_r = 0.7065
θ_r = sin^(-1)0.7065
θ_r = 44.95°
Thus; xonsidering refraction, distance from point B at which the laser beam strikes the lake-bottom is calculated from;
d = 4.3 tan44.95
d = 4.293 m
Answer: 87500J
Explanation:
Given that,
Power exerted by crane = 3,500 W
Time taken = 25 seconds
work done by crane = ?
Since power is the rate of work done per unit time, then power is workdone by the crane divided by the time taken.
i.e power = work / time
3,500 W = work / 25 seconds
Work = 3500W x 25 seconds
Work = 87500J
Thus, 87500 joules of work was done by the crane.