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.

   Esme's class robot crawls at a steady speed (it is in no hurry). Using the point (6 s, 30 m), how far does it crawl in 10 s?

   50 m
4. 4.

   Which object is faster, and how can you tell from the graph, Kira?

   • Neither, since both lines start at the same point (0 s, 0 m)
   • A, since its line stays lower on the graph the whole time
   • Cannot tell, since a graph shows distance and not speed
   • B: its steeper line gains 5 m a second, A only 2 m
5. 5.

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

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

6. Read this first

   Two readings (example data)

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

7. 6.

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

   5 m/s
8. 7.

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

   3 m/s
9. 8.

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

   6 m/s
10. 9.

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

    • Same velocity, since velocity is just how fast each car goes
    • Different speeds, since the two cars head in different ways
    • Same speed and the same velocity, since both are 20 m/s
    • Same speed, different velocities, since directions differ
11. 10.

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

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