List of top Physics Questions on Relativity

Ravi and Swati are twins and they are being separated at a rate of 0.80 c. Ravi and Swati each send out a radio signal once a year while Ravi is away. How many signals does Ravi receive for a trip of 15 years?
Consider a relativistic particle of rest mass 2m moving with a speed v along the x direction. It collides with another relativistic particle of rest mass m moving with the same speed but in the opposite direction. These two particles coalesce to form one particle whose rest mass M is
(\(\beta = \frac{v}{c}\), where c is the speed of light)
A particle is moving with a velocity \( 0.8c \) (where \( c \) is the speed of light) in an inertial frame \( S_1 \). Frame \( S_2 \) is moving with a velocity \( 0.8c \) with respect to \( S_1 \). Let \( E_1 \) and \( E_2 \) be the respective energies of the particle in the two frames. Then, \( \frac{E_2}{E_1} \) is ............ (Round off to two decimal places).
Three events, \( E_1(ct = 0, x = 0) \), \( E_2(ct = 0, x = L) \) and \( E_3(ct = 0, x = -L) \) occur, as observed in an inertial frame \( S \). Frame \( S' \) is moving with a speed \( v \) along the positive x-direction with respect to \( S \). In \( S' \), let \( t'_1, t'_2, t'_3 \) be the respective times at which \( E_1, E_2, \) and \( E_3 \) occurred. Then,
Two relativistic particles with opposite velocities collide head-on and come to rest by sticking with each other. Which of the following quantities is/are conserved in the collision?
A clock keeps correct time. With what speed should it be moved relative to an observer so that it may seem to lose 20 sec in 100 sec?
With what velocity should an electron move so that its kinetic energy equals its rest mass energy?
If the volume of a cube of side \( L_0 \) is \( L_0^3 \) as observed by an observer at rest relative to it, the volume as observed from a reference frame moving with uniform velocity \( 0.8c \) in a direction parallel to an edge of the cube will be:

Rod $R_1$ has rest length 1 m and rod $R_2$ has rest length 2 m. $R_1$ and $R_2$ move with velocities $+v\hat{i}$ and $-v\hat{i}$ respectively relative to the lab. If $R_2$ has a length of 1 m in the rest frame of $R_1$, $\frac{v}{c}$ is ................... (Specify answer up to two digits after decimal.)

Two events occur in frame $S$ at $(t_1 = 0,\ r_1 = 0)$ and $(t_2 = 0,\ x_2 = 10^8\mathrm{m}, y_2 = 0, z_2 = 0)$. Another frame $S'$ moves with $v = 0.8c$ relative to $S$. The time difference $(t_2' - t_1')$ in $S'$ is ................... s. (Specify answer up to two digits after decimal.)

Consider an inertial frame \( S' \) moving at speed \( c/2 \) away from another inertial frame \( S \) along the common x-axis, where \( c \) is the speed of light. As observed from \( S' \), a particle is moving with speed \( c/2 \) in the \( y' \) direction, as shown in the figure. The speed of the particle as seen from \( S \) is: 

Consider an inertial frame \( S' \) moving at speed \( c/2 \) away from another inertial frame \( S \) along the common x-axis, where \( c \) is the speed of light. As observed from \( S' \), a particle is moving with speed \( c/2 \) in the \( y' \) direction, as shown in the figure. The speed of the particle as seen from \( S \) is: 

Special theory of relativity treats problem involving
According to theory of relative mass of an object is