Physics Questions and Answers

The force which is centripetal
F = \(\frac{MV^2}{R}\)
=5 x 723.5
= 70

Since, force is 70 N when speed is 7m/s

Speed = ? when force 70N is trippled →  70 * 3 = 210N

210 = \(\frac{5×v^2}{3.5}\)
210 × 3.5 = 5 * v^2
735 ÷ 5 = v\(^2\)
v\(^2\) = 147
v =12.12m/s

R2 - P2 + Q2 = 122 + 52
= 144 + 25 = 169
∴R = √169 = 13N
∴ angle between the forces is 90^o

Electrical work W = QE,
Where Q is the quantity of change and E is the electromotive force.
∴ E = W = FxDQ_It
Where D is the displacement,I = current and t = time
But dimension of force,
= unit of mass x unit of Acceleration
= unit of mass xunit of velocityunit of time
= unit of mass x unit of displacement__unit of time x unit of time
ML/T2 = MLT-2
∴ Dimension of emf E
= MLT-2L = ML2T-3I-1__IT

From faradays law, M = itz
But mass, M = volume x density
and volume = cross sectional area x thickness
M = 118.8cm² x 10^-6 x 9 x 10³
∴ 118.8cm² x 10^-6 x 9 x 10³ = 10 x t x 3.3 x 10^-7
∴ (118.8 x 9) x 10^-7 = 10 x t x 3.3 x 10^-7

∴ t = \(\frac{118.8 \times 9}{ 3.3}\)

t = 324 seconds

Convert to minutes by dividing by 60

t = \(\frac{324}{60}\)

t = 5.4 sec

The inductive reactance is given as
Xl = 2πfl
= 2 x ⁵⁰/_π x 0.1
= 10Ω
Again from ohms law,
R = ^V/_I = ⁷⁵/_1.5 = 50Ω
∴ Thus the inductive reactance and the resistance are respectively 10Ω, and 50Ω