QUIZ Who wants to be a

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QUIZ Who wants to be a future millionaire??

• Learning physics is not too bad although you are
  already sickened.

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Question 1

• A mass of 400 grams is accelerated at 30 cm/s2.
  The force, in N, to accelerate this mass is

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The answer to Q1

• 0.12 newtons
• F ma 0.4 kg ? 0.3m/s2

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Question 2

• A walker walks 30 m from the origin toward the
  WEST to point A. She then walks from point A, 20
  m more toward the EAST to point B. What is the
  walkers total displacement from the origin?

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Answer to Q2

• 10 m toward the WEST (or -10 m)
• Distance and displacement are different!!

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Question 3

• A force of 56 N is directed 35 degrees NORTH of
  EAST. What is the EAST component of the force?

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Answer to Q3

• 45.9 N
• Do you remember when to use cos or sin for this
  type of problem?

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Question 4

• A momentum change is found as 5.8 kg m/s with the
  time interval, 0.22 s. What is the force acting
  on it during the time?

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Answer to Q4

• 26 N
• The change in momentum is equal to the impulse,
  F?s.

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Question 5

• What is the Keplers third law?
• The gravity is always the same with the equal
  period of the orbit.
• The square of the orbit period of a planet is
  proportional to the cube of the semi-major
  axis of its orbit.
• A line segment joining a planet and the Sun
  sweeps out equal areas during equal intervals of
  time.

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Answer to Q5

• (b)
• The formula is (T1/T2)2(r1/r2)3

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Question 6

• What is the meaning of the specific heat?

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Answer to Q6

• Specific heats depend on materials. The more
  specific heat it has, the harder to raise (or
  lower) the temperature with a certain heat.

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Question 7

• What are conservative and nonconservative forces?

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Answer to Q7

• A conservative force is derived from the
  correspondent potential energy, such as
  gravitational potential energy.
• A nonconservative force is not derived from the
  potential energy and its work depends on the path
  taken, such as frictional force, normal force,
  etc.

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Question 8

• A ball is projected from the origin with a
  velocity of 20.0 m/s at an angle of 60 degrees
  above the horizontal. What is the maximum height
  of the ball?

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Answer to Q8

• 15.3 m
• First, obtain the y-component of the velocity.
  Then, use v2v02-2gy, which is your favorite. ?

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Question 9

• A 4,000 kg satellite is traveling in a circular
  orbit 200 km above the surface of the earth. A
  3.0 gram marble is dropped inside the satellite.
  What is the force of gravity on the marble as
  viewed by the observers on the earth? (Me 5.98
  x 1024 kg, Re 6.37 x 106 m, G 6.67 x 10-11
  Nm2 /kg2)

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Answer to Q9

• 0.0277 N
• Use FGmM/r2 including the radius of the Earth.
  However, do not use the mass of the satellite.

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Question 10

• As for gravitational acceleration, 9.8 m/s2,
  which one of the following is true?
• Gravitational accel. is greater when an object is
  thrown up.
• Gravitational accel. is smaller when an object
  falls downward.
• Gravitational accel. is always the same wherever
  the object is placed on the Earth.

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Answer to Q10

• c) is the correct statement.
• 9.8 m/s2 is always the same (close to the
  surface) and directed to the center of the Earth.

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Question 11

• What is the law of conservation of mechanical
  energy?

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Answer to Q11

• The total mechanical energy in a system remains
  constant as long as the only forces acting are
  conservative forces.

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Question 12

• A 3.0-kg object is placed on horizontal and rough
  surface. If the coefficient of static friction is
  0.20, what is the force to move the object?

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Answer to Q12

• 5.88 N
• The frictional force is the normal force ? the
  coefficient of friction.
• The normal force in this case is mg.

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Question 13

• What is Newtons Law of Universal Gravitation?
  Choose one related equation.
• W mg
• FGmM/r2
• Fmv2/r
• Fma
• V2?r/T

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Answer to Q13

• b) is the correct equation.
• The law to describe the force between masses is
  Newtons Law of Universal Gravitation.

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Question 14

• Here is an equation
• ?Q/?T e s A (T14 - T24) .
• What are e and s called? Which situation can you
  use this equation?

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Answer to Q14

• e is emissivity.
• s is Stefan-Boltzmann constant, 5.670373
  10-8 kg s-3 K-4.
• This equation is used for radiation of heat.

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Question 15

• What is the apparent weight?
• It is always that the mass of the object times
  gravity.
• It is equal to weightlessness.
• It is the net mass of the object.
• It is the net weight you can feel how heavy it
  is.

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Answer to Q15

• d) is the correct description of apparent
  weight.
• In this sense, the apparent weight can be zero
  (weightlessness ) due to an inertial force.

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Question 16

• What is the work-(kinetic) energy theorem? Choose
  one of the best equation to describe it.
• KEf-KEiW
• KEfKEi
• fk?kn
• pf-piF?s
• QgainedQlost

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Answer to Q16

• a) is the correct expression to describe the
  work-(kinetic) energy theorem.
• You should be able to explain it in your own
  words.

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Question 17

• Find the impulse from the graph.

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Answer to Q17

• 0.9 N?s
• You can find the area, 60 N ? (0.09 0.06) s ?
  ½. (The area of the triangle)

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Question 18

• What is the following equation mean?
• Q/tkA(T1-T2)/?
• What is a condition that the equation can be
  valid?

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Answer to Q18

• That is used for conduction of heat. Q/t
  represents the rate of the heat transfer. The k
  is conductivity, A is area, ? is the length to
  conduct, etc.
• The equation assumes that the heat does not go
  away from the side of the object (conducting only
  one way).

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Are you ready for the final?

• Ask yourself why you have to use the specific
  equation to solve the problem.
• There are always concepts behind physics
  problems, so dont pick up numbers and plug in
  equations you randomly find from the equation
  sheet!!
• Make sure the definition of each physics term.