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What method is used to find relative value for any vector quantity?
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.
A body A is moving in North direction, while another body B is moving towards South. Velocity of A is greater than that of B. If North is taken as positive, which of the following relative velocities is positive?
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.
A point A is placed at a distance of 7 m from the origin, another point B is placed at a distance of 10 m from the origin. What is the relative position of B with respect to A?
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.
A car is moving with 20m/s velocity, another car is moving with a velocity of 50 m/s. What is the relative velocity of first car with respect to the second?
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.
The relative velocity of a body A with respect to a body B is 5 m/s. The absolute velocity of body B is 10 m/s. Both the bodies are moving in the same direction. What is the absolute velocity of body A?
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.
A small block is placed over another block which is moving with a velocity of 5m/s. What is the absolute velocity of the small block?
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 nonuniform. In that case it is better to work with the differential forms of velocity and acceleration.
An observer is sitting on a car moving with some constant velocity. The observer sees things around him, in the ____
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.
A truck is moving with 40 m/s velocity, a train is moving with a velocity of 80 m/s. How fast is the rain moving with respect to the truck?
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.
If two bodies are moving in opposite directions with nonzero velocities, which of the following statements is true?
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.
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