1. What is the weight of a 24kg mass on Mars if its surface gravitaional field = 3.5N/KG?
a) 235.2 N
b) 84 N
c) 24 kg
d) 6.86 kg
2. A space shuttle is placed in a circular orbit around the Earth. It then thrusts its engine and moves to a new orbit, as shown below. Which statement is true about the shuttle’s speed in this new higher orbit, if the new orbit is also circular?
A) The speed will have to be greater than in the lower orbit.
B) The speed will have to be less than in the lower orbit
C) The speed will have to be the same as in the lower orbit
D) The speed will have to increase continuously in the new orbit
3. Which of these statements best outlines Newton’s concept of escape velocity?
A) Vesc is the speed necessary to go into orbit
B) Vesc is the speed necessary to escape from the surface of a planet
C) Vesc is the speed necessary to become gravitationally unbound from a planet
D) Vesc is the speed of the gravitational force
4. Which statement below was not one of Einstein’s findings in the theory of relativity?
A) The aether is unnecessary
B) The speed of light in a vacuum is constant
C) The laws of physics are the same in all inertial frames of reference
D) Measurements of distance and time can’t be agreed on by any two observers
5. What occurs to the mass and acceleration of a rocket from lift-off to orbital insertion?
A) The mass decreases and the acceleration decreases
B) The mass decreases and the acceleration increases
C) The mass decreases and the acceleration remains constant
D) The mass remains constant and the acceleration increases
6. What type of motor includes a rotor which contains no coils of wire?
A) An AC induction motor
B) An AC coil motor
C) A DC induction motor
D) A DC coil motor
8. What is the function in a DC coil motor?
A) It allows the current to flow around many loops to increase torque
B) It allows the current to the coils to change direction
C) It provides a low friction contact with the external load
D) It provides the magnetic field within which the coil rotates
10. A simple hand –driven generator is made of a single coil turning within a uniform magnetic field. It is turned at a rate of 4 rotations per second. What occurs to the direction of the output current as the generator is turned?
A) The direction of the current flow does not change
B) The direction of the current flow changes four times every second
C) The direction of the current flow changes eight times every second
D) The direction of the current flow changes two times every second
12. Green light from a small laser is shone onto the surface of a certain metal X, but tests show that no photoelectrons are emitted from it. When blue light from a different laser illuminates the surface of metal X, tests show that now photoelectrons are released. Which of the following is most likely explanation for these experimental results?
A) The frequency of the green light was below the critical frequency for metal X
B) The intensity of the green light was below the critical intensity for metal X
C) The blue light had a greater intensity and power than the green light
D) Two of the above answers are correct
24*3.5
1. To find the weight of a mass on Mars, we need to multiply the mass by the surface gravitational field on Mars. In this case, the mass is given as 24 kg and the surface gravitational field on Mars is given as 3.5 N/kg. Therefore, the weight can be calculated as:
Weight = Mass * Gravitational Field
Weight = 24 kg * 3.5 N/kg
Weight = 84 N
So the answer is b) 84 N.
2. In a circular orbit, the speed of an object is determined by the balance between the gravitational force and the centrifugal force. When the shuttle moves to a higher orbit, the gravitational force decreases because it is further away from the Earth's center. Therefore, in order to maintain a circular orbit, the shuttle must increase its speed to balance the reduced gravitational force.
Therefore, the correct answer is A) The speed will have to be greater than in the lower orbit.
3. Newton's concept of escape velocity refers to the speed necessary to become gravitationally unbound from a planet. Therefore, the correct answer is C) Vesc is the speed necessary to become gravitationally unbound from a planet.
4. One of Einstein's findings in the theory of relativity was that the laws of physics are the same in all inertial frames of reference. Therefore, the correct answer is C) The laws of physics are the same in all inertial frames of reference.
5. From lift-off to orbital insertion, the mass of a rocket decreases as it burns fuel. According to Newton's second law of motion, the acceleration of an object is inversely proportional to its mass. Therefore, as the mass decreases, the acceleration of the rocket increases. Therefore, the correct answer is B) The mass decreases and the acceleration increases.
6. A motor that contains a rotor without coils of wire is an AC induction motor. Therefore, the correct answer is A) An AC induction motor.
8. In a DC coil motor, the function is to provide the magnetic field within which the coil rotates. Therefore, the correct answer is D) It provides the magnetic field within which the coil rotates.
10. As a hand-driven generator is turned, the direction of the output current changes. Since the generator is turned at a rate of 4 rotations per second, the direction of the current flow changes four times every second. Therefore, the correct answer is B) The direction of the current flow changes four times every second.
12. In order for photoelectrons to be emitted from a metal surface, the frequency of the light needs to be above the critical frequency for that specific metal. In this case, both the green light and blue light did not emit any photoelectrons, so we can conclude that the frequency of the green light was below the critical frequency for metal X. Therefore, the correct answer is A) The frequency of the green light was below the critical frequency for metal X.