Question

1. John (who is 95 kg) drives his car over an absurdly large half-circle speedbump with a radius of 5 meters. Given that his normal weight is 930 N and his apparent weight at the top of the speed-bump was 246 N, how fast did he drive over the speed bump?

2. When working in circular motion problems, what do we define as always being the positive direction?

3. When in circular motion, the net force points in what direction? What does this mean for the relationship between the weight & weight apparent at the top of a circular track? What does it mean when at the bottom?

4. John spins a sling around in a circle, preparing to release a projectile with a mass of 28 grams. If his sling is 60 cm long, and he is spinning it at a steady speed - so that the edge of the sling is moving at 30 m/s, what is the centripetal acceleration experienced by the projectile? What is the centripetal force acting on the projectile?

5. What is the best way to angularly accelerate a door? What is the worst way? Why?

6. What is the sign of a torque which would cause a clockwise rotation?

7. John (95 kg) sprints at the incredible speed of 11 m/s and tackles a black bear (220 kg) from behind, holding onto the bear as they travel. If the bear was travelling in the same direction as John, at a slow speed of 1 m/s prior to the tackle, what is the final velocity of both the bear and John after the tackle?

8. John, being an awakened bodhisattva who remains in this realm of suffering only to guide others to awakening, is perfectly balanced atop his sick ride – a unicycle – at rest. If a student throws him a marker, and he wants to maximize the velocity he gets from the marker, should he deflect it or catch it? Why?

9. A black bear is charging toward John at 10 m/s. John stops the bear by pushing against it for 2 seconds. If the bear has a mass of 220 kg, what was the average force John applied to stop the bear?

10. A meterstick is attached to the edge of a table by a pivot. A mass of 7 kg hangs at the 40 cm mark on the meterstick. If one were to apply an upward force at the 20 cm mark, what would the force need to be to put the system into equilibrium?

11. A spring is pulled with a force of 12 Newtons causing the spring to extend 6 cm. What is the spring constant?

12. Explain what the center of mass/gravity is. Can it move? Why does its location matter?

13. What makes something easier to tip over? What makes something harder to tip over? Explain why.

14. Define angular velocity, angular acceleration, period, frequency, moment of inertia, centripetal acceleration, and angular momentum.

15. How does angular velocity relate to linear velocity? How does angular acceleration relate to liner acceleration?

16. A sling with a length of 60 cm does 6 rotations per second. What is the speed that the stone at the end of the sling is travelling?

17. Compare and contrast ‘uniform circular motion’ with ‘nonuniform circular motion’.

18. Explain the conservation of momentum – what is conserved? In which cases does it apply?

19. A 50 kg mass is resting on a frictionless surface. An unknown force pushes the mass for 2 seconds until the mass reaches as velocity of 5 m/s. What is the initial momentum? What is the final momentum? What was the average force acting on the mass? What was the impulse acting on the mass?

20. The fastest pitch recorded in baseball was 105.1 MPH (46.98 m/s) by Aroldis Chapman. Assuming the baseball had a mass of 0.145 kg, what was the impulse he imparted on the baseball?

21. If one was to catch a baseball moving at such a speed with their barehand (assume the catch takes place over a time interval of 0.020 seconds), what force would the baseball impart onto the hand? If hand bones can break when under ~110 Newtons of force, can one safely catch such a ball?

Answer 1

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