The graph shows a rover's position. What is the rover's position, in m, at t = 6 s?
An airport shuttle train runs forward along a straight track at a steady 6 m/s. Near the end of the line it slows, stops for an instant, and rolls back the way it came, settling at 4 m/s in the reverse direction: velocity −4 m/s. One picture can hold that whole trip: how fast, and which way, at every moment.
This picture is a velocity-time graph. It plots the shuttle's velocity, in m/s, up the vertical axis against time, in s, along the horizontal axis.
The line's value at a moment is the velocity at that moment. At t = 2 s the line stands at 6 m/s: the shuttle's steady forward run.
The graph shows the velocity of a toy train. What is the train's velocity at t = 1 s?
Find t = 1 s on the time axis.
Go straight up to the line, then read across to the velocity axis: 2 m/s, above the time axis, so positive.
The train's velocity at t = 1 s is v = 2 m/s.
The graph shows the velocity of a delivery scooter. What is the scooter's velocity at t = 3 s? Enter the value in m/s, sign included.
The time axis itself marks v = 0. Values below it are negative velocities. From t = 8 s the shuttle's line lies at −4 m/s: the rolling-back stretch.
The graph shows the velocity of a river boat. What is the boat's velocity at t = 7 s?
Find t = 7 s on the time axis.
The line lies below the time axis there, so the velocity is negative.
Go straight down to the line, then read across: 5 units below zero.
The boat's velocity at t = 7 s is v = −5 m/s.
The graph shows the velocity of a cable car. What is the cable car's velocity at t = 2 s? Enter the value in m/s, sign included.
The graph shows the velocity of a canoe. What is the canoe's velocity at t = 7 s? Enter the value in m/s, sign included.
In earlier grades you saw graphs of speed against time. A velocity-time graph tells you more. Velocity can be negative as well as positive, so the line can dip below the time axis, as the shuttle's line did when it rolled back at −4 m/s. Every velocity-time graph reads the same way.
The graph shows the velocity of a tractor. What is the tractor's velocity at t = 6 s?
The graph shows the velocity of a water taxi. What is the taxi's velocity at t = 8 s?
The graph shows the velocity of a harbor tug. What is the tug's velocity at t = 6 s?