Solve for speed, distance or time

Answer Key - Grade 8 Science Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Ari's toy car rolls at a steady speed. Using the point (4 s, 12 m) on its graph, how far does it roll in 10 s?

   30 m
2. 2.

   Bo rides a scooter at a steady speed. Using the point (5 s, 20 m) on the graph, how far does the scooter go in 8 s?

   32 m
3. 3.

   What is the object doing from 2 s to 4 s on the graph, Jun?

   • Moving forward, but very slowly indeed
   • Stopped: its distance stays at 10 m
   • Moving back toward the start at a slow pace
   • Moving along at a steady 10 m/s, since the line is at 10
4. 4.

   What does the falling line from 4 s to 8 s show, Luz?

   • The object is moving away from the start more slowly
   • The object is coming back toward the start at 4 m/s
   • A speed of 0 m/s, since it ends at 0 m
   • The object is slowing down to a stop

5. Read this first

   Two readings (example data)

   reading	time (s)	distance from start (m)
   first	2	20
   second	10	60

6. 5.

   Milo's bike rides at a steady speed past a marker. Using the two readings, what is the bike's speed?

   5 m/s
7. 6.

   A lab cart rolls at a steady speed along a track. Noah records two readings. What is the cart's speed?

   3 m/s
8. 7.

   Pia's toy boat drifts at a steady speed across a pond. Using the two readings, what is its speed?

   6 m/s
9. 8.

   Two cars each travel at 20 m/s, one heading north and one heading east. How do their speeds and velocities compare, Ren?

   • Same speed, different velocities, since directions differ
   • Same speed and the same velocity, since both are 20 m/s
   • Same velocity, since velocity is just how fast each car goes
   • Different speeds, since the two cars head in different ways
10. 9.

    Tala rolls a ball 12 m east, and it rolls 12 m back west, in 8 s in all. What are its average speed and average velocity?

    • Speed 0 m/s and velocity 0 m/s, since it ends where it began
    • Speed 1.5 m/s and velocity 1.5 m/s, since 12 m takes 8 s
    • Speed 3 m/s and velocity 3 m/s east, since it moved 3 m each second
    • Speed 3 m/s and velocity 0 m/s, since it ends where it began
11. 10.

    A car drives around a circular track at a steady 15 m/s. Is the car's velocity steady, Zee?

    • Yes, since its speed is steady, the velocity is steady too
    • Yes, since it stays on the same track the whole way
    • No, since its speed keeps changing as it goes around
    • No: speed is steady, but the direction keeps changing