Question

13. What is the instantaneous velocity and instantaneous speed at t 4? 14. For what time interval(s) is the velocity (a) negative? (b) positive? (c) zero?

Answer 1

The diagram is visible in a very faint manner.

13.The instantaneous velocity at t=4 is zero since the body remains at 9m in time interval from t = 3 to 5. Please note that instant velocity is always measured by the slope of the distance versus time graph.In this case the slope is zero

14.

a) The velocity is negative from t= 5 to t=7 , since slope of the graph here is uniformly negative at -3m/s

b) The Velocity is positive from t =0 to t=1 and has value +4m/s . It is +0.5m/s from t=1 to t=3 sec. It is positive from t= 7 to t=10 sec, where slope and velocity are +1 m /s

c) The velocity is zero from t =3 sec to t= 5 sec , because in this time interval no distance is travelled