Question

The graph above shows position versus time for an object moving along a straight line. During which time interval(s) is the object's speed increasing?
I. $0$ to $1$ seconds
II. $1$ to $2$ seconds
III. $2$ to $3$ seconds

• A. I only
• B. II only
• C. III only
• D. I and III only

Answer 1

The correct option is C III only

Slope of the position-time graph gives the instantaneous velocity of the object.

During $0<t<1$ s : Slope of the curve is constant, thus the velocity of the object is also constant.

During $1<t<2$ s : Slope of the curve is zero, thus the velocity of the object is zero.

During $2<t<3$ s : Slope of the curve is positive and increasing, thus the velocity of the object increases during $1$ to $2$ seconds.

Hence option C is correct.