Question

A graph in Fig. shows the change in position with time for two objects A and B moving in a straight line from 0 to 10 seconds. Choose the correct option(s).

Options

• The average velocity of both over the 10 s time interval is equal since they have the same initial and final positions.

• The average speeds of both over the 10 s time interval are equal since both cover equal distance in equal time.

• The average speed of A over the 10 s time interval is lower than that of B since it covers a shorter distance than B in 10 seconds.

• The average speed of A over the 10 s time interval is greater than that of B since B’s speed is lower than A’s in some segments.

Answer 1

The average velocity of both over the 10 s time interval is equal since they have the same initial and final positions.

The average speeds of both over the 10 s time interval are equal since both cover equal distance in equal time.

Explanation:

(1) Average velocity = `"displacement"/"time travel"`. Both have equal displacements and the same time period (10 s) since their initial and final positions are the same. They therefore have equal average velocities.

(2) The total distance travelled by each object equals the amount of its displacement since they both travel in the same direction on a straight line. Since both displacements and times are equal, their average speeds are also equal because their total distances are equal.

(3) and (4) are incorrect since neither object has a higher or lower average speed than the other, since they both go the same distances in the same amount of time.