Acceleration

Answer Key - Grade 11 Science Worksheet

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

1. 1.

   East is positive. A cyclist reads 4 m/s at t = 2 s and -6 m/s at t = 10 s, after turning around. What is the acceleration, Bo?

   -1.25 m/s²
2. 2.

   East is positive. A ball arrives at 25 m/s at t = 0.1 s and leaves at -18 m/s at t = 0.12 s. What is its acceleration, Esme?

   -2150 m/s²
4. 3.

   The curved velocity-time graph rises, then levels at 4 s. What are the average acceleration from 0 to 4 s and the acceleration at 4 s, Kira?

   • Average 4 m/s²; at 4 s it is still 4 m/s²
   • Average 4 m/s²; at 4 s it is 16 m/s²
   • Average 4 m/s²; at 4 s the slope is 0
   • Average 16 m/s²; at 4 s the slope is 0
5. 4.

   Using the same curve, in which one-second step is the average acceleration largest, and how large, Luz?

   Use the picture in question 3.

   • 0 to 4 s: 4 m/s², the longest step
   • The first second: 16 m/s²
   • The first second: 7 m/s²
   • The last second: −1 m/s², the final slope
6. 5.

   A car moves at 20 m/s. The driver reacts for 0.80 s, then brakes at 5.0 m/s². How far does it travel before stopping, Milo?

   • 40 m, leaving out the reaction time
   • 96 m, using 20 × 4.0 s for the braking part
   • 56 m: 16 m before braking and 40 m while braking
   • 16 m, the reaction distance alone, before it stops
7. 6.

   East is positive. A cart starts at v = +6 m/s with a constant a = −2 m/s². What is it doing at t = 5 s, Noah?

   • Moving east at 4 m/s and slowing
   • Moving west at 4 m/s and slowing
   • Moving west at 4 m/s and speeding up
   • At rest, since a negative a brings v to zero
8. 7.

   A cart speeds from 3.0 m/s to 11 m/s over 28 m. The time is unknown. Which equation fits, and what is a, Pia?

   • v² = v₀² + 2ad, giving a = 1.0 m/s²
   • v = v₀ + at, giving a = 0.29 m/s²
   • v² = v₀² + 2ad, giving a = 2.0 m/s²
   • v² = v₀² + 2ad, giving a = 4.0 m/s²

9. Read this first

   Two balls dropped from rest (example data)

   time (s)	ball A in vacuum speed (m/s)	ball B in air speed (m/s)
   0	0	0
   1	9.8	9.5
   2	19.6	17.2
   3	29.4	23.4

10. 8.

    Ren drops two balls and records speed each second. Ball A falls in a vacuum, ball B in air. Which statement fits the table?

    • Both have a = 9.8 m/s², since gravity is the same
    • B's acceleration shrinks each second; A's stays 9.8 m/s²
    • A's acceleration grows because its speed grows
    • B is slowing down, since its gains get smaller
11. 9.

    A sign says: "Raising the limit from 30 to 40 mph adds only a third more braking distance." Judge the claim, Tala.

    • Supported: a third more speed gives a third more distance
    • Not supported: it is about 178% more
    • Not supported: it is about 133% more
    • Not supported: distance scales as v², so about 78% more
12. 10.

    A ball is thrown down at 4.0 m/s from a bridge and hits the water after 2.0 s. How high is the bridge, Zee?

    • About 47 m, using g t² without the one half
    • About 28 m: 8.0 m from the throw, 19.6 m from gravity
    • About 20 m, if the ball were simply dropped
    • About 24 m, the final speed used as the height