Compare designs that reduce the force in a collision

Answer Key - Grade 11 Science Worksheet - Challenge Me

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

1. 1.

   The same toy cart is stopped by a hard bumper in 0.05 s or a soft bumper in 0.2 s. How many times bigger is the hard bumper's average force, Ari?

   4 times
2. 2.

   The same toy cart is stopped by a hard bumper in 0.1 s or a soft bumper in 0.3 s. How many times bigger is the hard bumper's average force, Esme?

   3 times
4. 3.

   Using the bumper table, does D's 15 N fit F = Δp ÷ Δt, Jun?

   • Yes: 0.4 × 6 = 15
   • No: it should be 2.4 N
   • Yes: 6 ÷ 0.4 = 15 N
   • No: it should be 60 N
5. 4.

   Using the bumper table, why is spring bumper B's force 120 N instead of 6 ÷ 0.1 = 60 N, Kira?

   Use the picture in question 3.

   • The cart is heavier with B
   • The bounce doubles Δp to 12 kg·m/s
   • Springs add their own energy
   • The table is wrong
6. 5.

   Using the bumper table, foam bumper A is tried on a 4 kg cart at 3 m/s with the same 0.2 s stop. Does it still meet the 50 N limit, Luz?

   Use the picture in question 3.

   • Yes: it drops to 15 N
   • No: the force becomes 60 N
   • No: the force becomes 600 N
   • Yes: it stays 30 N
7. 6.

   Milo says a stiffer bumper that stops carts faster is gentler. Agree or disagree?

   • Agree: quicker stops are gentler
   • Agree: the lightest bumper wins
   • Disagree: a faster stop means a bigger force
   • Agree: bouncing back is gentler too
8. 7.

   Noah says a springy bumper that bounces carts back is gentler than foam. Agree or disagree?

   • Disagree: a bounce makes Δp bigger
   • Agree: quicker stops are gentler
   • Agree: just the force matters, not the limits
   • Agree: bouncing is gentler
9. 8.

   How could Ren improve foam bumper A to lower its force while staying under 100 g?

   • Add a spring so it bounces
   • Use a softer foam of the same mass
   • Make it from a heavier, thicker block
   • Replace it with wood
10. 9.

    How could spring bumper B be changed so it stops carts without bouncing them back, Tala?

    • Add a damper that soaks up the push-back
    • Use a stiffer spring that stores more energy
    • Remove the spring
    • Paint it
11. 10.

    After redesigning a bumper, what should Zee do next?

    • Change the limits
    • Test it on a faster cart instead
    • Test it the same way and compare
    • Assume it works