Name: __________________________ Date: _____________



1.
When sitting still on the ground, a tricycle is in a state of
A.
unstable dynamic equilibrium
B.
dynamic equilibrium
C.
stable static equilibrium
D.
unstable static equilibrium


2.
A three – wheeler is
A.
statically stable and dynamically unstable
B.
statically unstable and dynamically stable
C.
both statically and dynamically unstable
D.
both statically and dynamically stable


3.
A motorcycle is
A.
statically stable and dynamically unstable
B.
statically unstable and dynamically stable
C.
both statically and dynamically unstable
D.
both statically and dynamically stable


4.
In studying many martial arts, it is necessary to practice efficient and safe postures. One important concept related to how one should stand is that the feet should be reasonably far apart, because
A.
the base of support is wider, thus stabilizing the person.
B.
the weight on each foot will be less than when standing normally.
C.
the weight on each foot will be more than when standing normally.
D.
the friction force increases, giving the person more traction.


5.
At various times in the news it has been reported that certain vehicles are susceptible to rolling over. The physical mechanism that is responsible for rollovers is
A.
Frictional torques about the driver only.
B.
Frictional torques from the tricycle on the road acting below the road's center of mass.
C.
Frictional torques from the road on the tricycle about its center of mass, which is below the rider.
D.
Strong air currents simply blowing the system over.


6.
It is important for cyclists to lean their bicycles while negotiating sharp turns because
A.
the torque created by their leaning balances out the frictional torque from the road which would tend to flip them.
B.
the torque created by their leaning balances out their weight and holds them up.
C.
their tires flatten out, thus getting better traction on the road.
D.
they increase their static stability


7.
You are riding a multi-speed bicycle up a steep hill that's 100 m high and want to do as little work as possible on your way up the hill.
A.
You should choose the largest crank sprocket (attached to the pedals) and the smallest freewheel sprocket (attached to the rear wheel).
B.
You should choose the smallest crank sprocket (attached to the pedals) and the largest freewheel sprocket (attached to the rear wheel).
C.
You should choose the largest crank sprocket (attached to the pedals) and the largest freewheel sprocket (attached to the rear wheel).
D.
Your choice of gears doesn't matter because you'll do the same amount of work climbing the hill no matter which gear you choose.


8.
You go to a quick – fix garage to get your brakes worked on. When your tires are re – installed, the mechanic forgets to put the lug nuts on your tires. Although nobody gets hurt, a tire comes off your car when you are traveling fairly rapidly and it is able to roll through a very large distance, even hitting bumps and objects in the way. Please explain why the tire can roll so far without tipping over.

Answer:


9.
Please explain why tricycles are better at sitting still than bicycles are, but bikes are the vehicles of choice when you want to be moving.

Answer:


10.
Astronauts in the space shuttle feel weightless because
A.
They are so far away from the center of the Earth.
B.
they are in a constant state of free – fall.
C.
they are moving very rapidly.
D.
there is no atmosphere where they are.


11.
The Earth is about 81 times as massive as the Moon. Suppose the earth and Moon are 10 distance units apart. If you were an astronaut between the Earth and Moon at how many distance units from the Moon will the gravitational attraction on you from the two bodies be equal and opposite?(!!! this question has been corrected on the date 28/11/06 )
A.
81 units
B.
9 units
C.
19 units
D.
1 unit


12.
The Earth is about 81 times as massive as the Moon. Suppose the earth and Moon are 240,000 miles apart. If you were an astronaut between the Earth and Moon at what distance from the Moon will the gravitational attraction on you from the two bodies be equal and opposite?(!!! this question has been corrected on the date 28/11/06 )
A.
216,000 mi
B.
2963 mi
C.
24,000 km
D.
24,000 miles


13.
Suppose you are spending your weekend on roller skates trying to get momentum from somewhere. Which of the following will give you momentum in the north direction?
A.
Throwing your keys southward.
B.
Throwing your keys northward.
C.
Bending down and throwing your keys straight up.
D.
(B) or (C).


14.
You are substitute teaching for your spouse and are using balloons to demonstrate how rockets work. The balloons are blown up and released so that the air can leave them rapidly. Why do the balloons fly all around, even though the balloon does not have a surface to push against?

Answer:


15.
Suppose you have two identical particles that attract each other with a certain gravitational force. Now you move them so they are three times as far apart as they were originally, but the force between them stays the same. What is one way in which the masses might change so the force could remain constant?

Answer:


16.
You and a friend are on roller skates. You are in a room and have a basketball and are standing in between two parallel walls. By touching only the ball, describe how you would make yourselves come together.

Answer:


17.
The maximum speed of a rocket whose massspacecraft is 10 times of its massfuel can achieve is (!!! this question has been corrected on the date 28/11/06 )
A.
the speed of light
B.
the speed of sound.
C.
equal to the speed of its exhaust plume.
D.
less than the speed of its exhaust plume.
E.
greater than the speed of its exhaust plume but less than the speed of light.



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