Question

The position vector of a point in the frame S moving with constant velocity 10 cm/s along the X-axis is given by (11,9.8) cm. The position with respect to S if the two frames were coincident only 1/2 second earlier.

• A. (11, 9.8)
• B. (16, 9.8)
• C. (16, 13.10)
• D. (11, 13.10)

Hint:

When calculating position changes due to uniform motion, always consider the direction of motion and coordinate axes involved.

Answer 1

The Correct Option is B

To find the position of a point half a second earlier in a frame moving at \(10 \, \text{cm/s}\), subtract the displacement due to the frame's motion from the current position. Here, the displacement in half a second is:
\[\Delta x = 10 \, \text{cm/s} \times 0.5 \, \text{s} = 5 \, \text{cm}\]
Thus, the position half a second earlier, moving backward along the x-axis, is:
\[x_{\text{earlier}} = 11 \, \text{cm} + 5 \, \text{cm} = 16 \, \text{cm}\]
The y-coordinate remains unchanged as the movement is only along the x-axis.