Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
Concepts Of Physics MCQ Edition [Volume 2]PhysicsThe Special Theory of Relativity

Measured at rest, a rod has an exact length of 1 m . Determine its length when it travels at a speed of 3 10^7 m s ⁻¹ .

Options

  1. A0.990 m
  2. B0.995 m
  3. C1.010 m
  4. D1.005 m

Correct answer

B. 0.995 m

Step-by-step solution

Given rest length of the rod, L₀ = 1 m Speed of the rod, v = 3 10^7 m s ⁻¹ Speed of light, c = 3 10^8 m s ⁻¹ Using the length contraction formula: L = L₀ 1 - v^2 c^2 Substituting the given values: L = 1 1 - ( 3 10^7 3 10^8 )^2 L = 1 - (0.1)^2 L = 1 - 0.01 L = (1 - 0.01)^ 1/2 Using the binomial approximation (1 - x)^n 1 - nx for x 1 : L 1 - 1 2 (0.01) L 1 - 0.005 = 0.995 m

Practice The Special Theory of Relativity on Quantrex Academy →

More from The Special Theory of Relativity

A yogi's guru resides in a Karakoram cave, located 1000 km away from the house of the yogi. The yogi asserts that whenever he thinks about his guru, the guru instantly knows about Measured at rest, a rod has an exact length of 1 m . Determine its length when it travels at a speed of 3 10^5 m s ⁻¹ .Measured at rest, a rod has an exact length of 1 m . Determine its length when it travels at a speed of 3 10^6 m s ⁻¹ .A shop owner measures a suitcase kept on a rack to be 50 cm 25 cm 10 cm . A traveller takes this suitcase on a train travelling with a velocity of 0.6c . If the suitcase is orienteA shop owner measures a suitcase kept on a rack to be 50 cm 25 cm 10 cm . A traveller takes this suitcase on a train travelling with a velocity of 0.6c . If the suitcase is orienteA person standing on a platform notes that a train travelling with a velocity of 0.6c requires one second to pass by them. Determine the length of the train as seen by this person.A person standing on a platform notes that a train travelling with a velocity of 0.6c requires one second to pass by them. Determine the rest length of the train.An aeroplane flies over a rectangular field of dimensions 100 m 50 m , moving parallel to its length. Determine the speed of the plane such that the field appears as a square in th Full The Special Theory of Relativity list All Concepts Of Physics MCQ Edition [Volume 2] PYQs