QUIZ Who wants to be a “ future ” millionaire??

QUIZ Who wants to be a “future” millionaire?? Learning physics is not too bad although you are already sickened.

Question 1 • A mass of 400 grams is accelerated at 30 cm/s2. The force, in N, to accelerate this mass is…

The answer to Q1 • 0.12 newtons F = ma = 0.4 kg  0.3m/s2

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 walker’s total displacement from the origin?

Answer to Q2 10 m toward the WEST (or -10 m) Distance and displacement are different!!

Question 3 • A force of 56 N is directed 35 degrees NORTH of EAST. What is the EAST component of the force?

Answer to Q3 45.9 N Do you remember when to use cos or sin for this type of problem?

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?

Answer to Q4 26 N The change in momentum is equal to the impulse, Fs.

Question 5 • What is the Kepler’s third law? • The gravity is always the same with the equal period of the orbit. • The square of theorbit periodof a planet is proportional to the cube of thesemi-major axisof its orbit. • A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.

Answer to Q5 (b) The formula is (T1/T2)2=(r1/r2)3

Question 6 • What is the meaning of the specific heat?

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.

Question 7 • What are conservative and nonconservative forces?

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.

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?

Answer to Q8 15.3 m First, obtain the y-component of the velocity. Then, use v2=v02-2gy, which is your favorite. 

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)

Answer to Q9 0.0277 N Use F=GmM/r2 including the radius of the Earth. However, do not use the mass of the satellite.

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.

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.

Question 11 • What is the law of conservation of mechanical energy?

Answer to Q11 The totalmechanical energyin a system remains constant as long as the only forces acting are conservative forces.

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?

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.

Question 13 • What is Newton’s Law of Universal Gravitation? Choose one related equation. • W = mg • F=GmM/r2 • F=mv2/r • F=ma • V=2r/T

Answer to Q13 b) is the correct equation. The law to describe the force between masses is Newton’s Law of Universal Gravitation.

Question 14 • Here is an equation: ΔQ/ΔT = e σ A (T14 - T24) . What are e and σ called? Which situation can you use this equation?

Answer to Q14 e is emissivity. σ is Stefan-Boltzmann constant, 5.670373 × 10-8kg s-3K-4. This equation is used for radiation of heat.

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.

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.

Question 16 • What is the work-(kinetic) energy theorem? Choose one of the best equation to describe it. • KEf-KEi=W • KEf=KEi • fk=kn • pf-pi=Fs • Qgained=Qlost

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.

Question 17 • Find the impulse from the graph.

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)

Question 18 • What is the following equation mean? Q/t=kA(T1-T2)/ What is a condition that the equation can be valid?

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).

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 don’t pick up numbers and plug in equations you randomly find from the equation sheet!! • Make sure the definition of each physics term.

QUIZ Who wants to be a “ future ” millionaire??