Test: Relative Velocity - ACT MCQ

To find the relative value of any quantity, vector difference is used. The relative value is defined as the subtraction of the remaining vector from the vector whose relative value is to be calculated with respect to the remaining vector.

The formula for relative velocity is, Vector V_R = Vector V_A – Vector V_B. The velocity of A is greater in magnitude hence the relative velocity of A will be positive. The direction of the relative velocity will be Northwards.

Relative displacement of B with respect to A = Displacement of B - Displacement of A. On solving we get, relative displacement = 3 m. Hence B is placed at a distance of 3 m from A.

The formula for relative velocity is V_R = Vector V_A – Vector V_B. Assuming the cars move in the same direction, the relative velocity = 20 - 50 = -30 m/s. The relative velocity of the second with respect to the first car is 30 m/s.

Here we will use the formula for relative velocity, Vector V_R = Vector V_A – Vector V_B. Since both the bodies are moving in the same direction, the velocity vectors are of the same sign. V_R = 5, V_B = 10, therefore, V_A = 15m/s.

The absolute velocity of the small block is the same as that of the block moving with 5m/s. This is because absolute velocity is studied with respect to the ground frame. The relative velocity of the small block with respect to the other block is zero.

The three equations of motion are valid for uniformly accelerated motion. The equations do not work in situations where the acceleration is non-uniform. In that case it is better to work with the differential forms of velocity and acceleration.

The observer is not stationary with respect to ground. The observer is stationary with respect to the frame of the moving car, i.e., to the relative frame of reference. The observer will see everything around him/her with respect to the relative frame of reference.

Here we need to find the relative velocity of the train with respect to the truck is V_R = V_A-V_B, V_B = 40, V_A = 80. On solving we get, V_R = 40 m/s. Hence the train will move faster by 40 m/s.

The formula for relative velocity is, Vector V_R = Vector V_A – Vector V_B. When both the velocities are opposite in direction, the equation becomes V_R = V_A – (-V_B). Hence the magnitudes add up making the relative velocity greater than the absolute velocity of any of the two bodies.