Answer:
5 W
Explanation:
The formula of the power is:
● P = W/t
W is the work and t is the time needed to do it(in seconds)
Let's calculate first the work that the force exerced:
W = Vector F . Vector d
D is the distance ( here 400 cm wich is 4 m)
Make a representation to see how are the vectors F and V.(picture below)
The vector F and d are colinear since Den is pushing the desk on the ground.
● W = 4 × 10 = 40 J
J is Joule
■■■■■■■■■■■■■■■■■■■■■■■■■■
● P = W / t
● P = 40/ 8
● P = 5 W
Answer:
option (B)
Explanation:
Intensity of unpolarised light, I = 25 W/m^2
When it passes from first polarisr, the intensity of light becomes

Let the intensity of light as it passes from second polariser is I''.
According to the law of Malus

Where, θ be the angle between the axis first polariser and the second polariser.

I'' = 11.66 W/m^2
I'' = 11.7 W/m^2
Answer:B. Increased the amount of charge.
Explanation:
Answer:
a)
b)
c) 0 J/K
d)S= 61.53 J/K
Explanation:
Given that
T₁ = 745 K
T₂ = 101 K
Q= 7190 J
a)
The entropy change of reservoir 745 K

Negative sign because heat is leaving.

b)
The entropy change of reservoir 101 K


c)
The entropy change of the rod will be zero.
d)
The entropy change of the system
S= S₁ + S₂
S = 71.18 - 9.65 J/K
S= 61.53 J/K
Explanation:
Given that,
Initial speed of the sports car, u = 80 km/h = 22.22 m/s
Final speed of the runner, v = 0
Distance covered by the sports car, d = 80 km = 80000 m
Let a is the acceleration of the sports car. It can be calculated using third equation of motion as :




Value of g, 


Hence, this is required solution.