| Question | Answer |
| An object is executing a circular motion. What is the direction of instantaneous linear speed? | The direction is along the tangent to the circumference at any instant.
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What are the official SI units for tangential velocity? What is the SI unit for angular velocity? What is the common unit for angular velocity?2 | (A)m/s or km/h, (B)rads/s, (C) RPM or revolutions per minute.2
| Explain why the wheels on a railroad car are beveled in relation to their tangential speed.3 | Since the wheels are slightly tapered, the different tangential speeds cause them to self-correct toward the center of the track.3
| What happens to the rotational inertia/moment of inertia if the mass relative to the axis of rotation is closer to the center than the ends.4 | The rotational inertia/moment of inertia would be less if the mass were located in the center relative to the axis of rotation.4
| An object is rolling down an incline, what is the relationship between its acceleration and its rotational inertia?5 | The higher the rotational inertia, the lower it its acceleration.5
| When does a force produce zero torque?6 | When the lever arm distance is zero.6
| In relation to physics, explain why the Leaning Tower of Pisa does not topple over?7 | The center of gravity or center of mass is still over the base of support. So, the tower is in stable equilibrium.7
| In terms of center of gravity, support base, and torque, why can't you stand with your heels and back to a wall and then bend over to touch your toes and return to your stand-up position?8 | In attempting to do so, your CG extends beyond your support base, so you topple.8
| Is it an inward force or an outward force that is exerted on the clothes during the spin cycle of an automatic washing machine?9 | The force on the clothes is inward.9
| If you are not wearing a seat belt in a car that rounds a curve, and you slide across your seat and slam against a car door, what kind of force is responsible for your slide: Centripetal, centrifugal, or no force?10 | No force is responsible; you tend to move forward in a straight line and the car curves into you.10
| How can gravity be simulated in an orbiting space station?11 | Rotational motion results in a centrifugal force that behaves like the force of gravity.11
| What is the law of inertia for rotating systems in terms of angular momentum?12 | The angular momentum of a system remains constant when no net torque acts.12
| Calculate the torque produced by a 100 N perpendicular force at the end of a 0.3 m long wrench.13 | 30 N-m13
| How does the torque produced change if the force reduces to 50 N while keeping the length of the wrench unchanged at 0.3 m.14 | 15 N-m.15
| A horizontal string whirls a 1 kg can in a circle of radius 2 m with a speed of 2 m/s. Calculate the tension in the string.16 | 2 N16
| Calculate the force of friction that keeps an 80 kg person sitting on the edge of a horizontal rotating platform when the person sits 2 m from the center of the platform and has a tangential velocity of 3 m/s.17 | 360 N17
| Calculate the angular momentum of a 1 kg can in a circle of radius 2 m with a speed of 2 m/s.18 | 4 kgxm^2/s18
| If we have an 80 kg person sitting on the edge of a horizontal rotating platform 2 m from the center and a tangential speed of 3 m/s, what would happen to the person's angular momentum if the velocity were doubled? Calculate.19 | 960 kgxm^2/s.19
| To tighten a bolt, you push with a force of 80 N at the end of a wrench handle that is 0.25 m from the axis of the bolt. What is the torque?20 | 20 Nxm.20
| A youngster who has entered a soapbox derby (in which four-wheel, unpowered vehicles roll from rest down a hill) asks if large massive wheels or lightweight ones should be used. Also, should the wheels have spokes or be solid? What advice do you offer?21 | Advise the youngster to use wheels with the least rotational inertia. Thus, lightweight solid ones without spokes.21
| Explain what would happen to a satellite orbiting the Earth if its tangential velocity were suddenly to drop to zero? Explain.22 | The satellite would drop straight into the Earth due to the gravitational pull.22
| According to the formula for gravitational force, what would happen to force if the mass on one planetary body were to suddenly increase in mass by a factor of five times whilst the other remained the same?23 | It would increase by a factor of five.23
| Briefly describe the technique used by Cavendish and Jolly to calculate G.24 | Basically, they rolled an object of much larger mass under an object with a smaller mass and noted the difference in measurement based on a scale.24
| According to the inverse-square law, what would be your exact weight if you were twenty times the distance from the Earth?25 | Answers will vary. Students should convert kg to N and then calculate their weight in reference to distance.25
| Explain briefly why astronauts experience sustained weightlessness in orbit around the Earth.26 | They are continually falling around the Earth and face no supporting force.26
| Discuss several health effects after being in low g's for an extended period of time.27 | Answers will vary; muscle mass reduction, bone density decrease, dementia, possible liver damage, etc.27
| Specifically, what causes ocean tides?28 | The difference in the gravitational pull between the moon and the Earth.28
| Distinguish between the tidal forces produced by the Sun and those produced by the Earth.29 | The Sun is 50% less effective. It is further away from the Earth. The gravitational forces upon the Earth affect all surfaces equally. No difference, no or little tides.29
| Distinguish between Spring Tides and Neap Tides.30 | Spring tides result from the Sun, the Earth, and the Moon being in alignment. Neap tides occur when the Moon, the Earth, and the Sun are at 90 degrees. Spring tides = Higher high tides, lower low tides. Neap tides = Lower high tides, higher low tides.30
| Why would tidal forces upon the Earth cause a slight increase in earthquakes and volcanic eruptions?31 | The Earth is a semi-molten liquid which rises and falls slightly; 25 cm.31
| Explain in detail why we only see one side or hemisphere of the Moon.32 | The CG and CM are in different places on the moon. Thus, the Earth produces torque and forces the moon into alignment with Earth's gravitational field.32
| How did Einstein explain gravity according to his theory of relativity?33 | He envisioned spacetime in 4D. Objects with large mass produce large warps in spacetime. Objects that get close are either curved or get pulled in orbit.33
| Describe how and under what conditions a blackhole is formed.34 | A collapsing star with large mass, slow rotation, and constant mass.34
| Cite two pieces of evidence that support the existence of black holes.35 | Binary star systems, black holes at the center of each galaxy, correlation between black holes and sigma, gravitational effect witnessed by nearby matter/stars.35
| What did Stephen Hawking state about the creation of the universe and how it would end?36 | Began with the big bang and will end with a black hole.36 |
