Physics MCQ series - 12

111:  Which one of the following is the name of a device used to measure voltage without drawing ANY current from the circuit being measured?  Is it:

w) a watt-meter

x) a galvanometer

y) an ammeter

z) a potentiometer


ANSWER:  Z -- A POTENTIOMETER


112:  Lenz's law is an example of the law of conservation of one of the following.  Is it conservation of?

w) mass
x) charge
y) momentum
z) energy

ANSWER:  Z -- ENERGY


113:  After a projectile is fired horizontally near the earth's surface, the horizontal component of its velocity, neglecting any air resistance:
 

w) Increases steadily

x) Decreases steadily

y) First decreases, then increases

z) remains constant

ANSWER:  Z -- REMAINS CONSTANT


114:  Two bodies are moving in circular paths of equal radii.  If the speed of the first body is twice that of the second, the centripetal acceleration of the first body is how many times greater than that of the second body?

ANSWER:  4Science Bowl PHYSICS

115:  Two bodies of equal mass are moving in circular paths at equal speed.The first body moves in a circle whose radius is twice as great as that of the second.  The ratio of the centripetal or radial acceleration of the first body to that of the second is: 


w) 1 to 4

x) 1 to 3

y) 1 to 2

z) 1 to 1

ANSWER:  Y -- 1 TO 2


116:  A force applied to a rocket gives it an upward acceleration equal to 2 times the acceleration of gravity.  The magnitude of the force is equal to:


w) the weight of the rocket

x) twice the weight of the rocket

y) three times the weight of the rocket

z) four times the weight of the rocket

ANSWER:  Y -- THREE TIMES THE WEIGHT OF THE ROCKET


117:  A satellite is observed to move in a circle about the earth at a constant speed.  This means that the force acting upon it is:

w) zero

x) parallel to the direction of the satellite's instantaneous velocity

y) perpendicular to the direction of the satellite's instantaneous velocity

z) none of the above


ANSWER:  Y -- PERPENDICULAR TO THE INSTANTANEOUS DIRECTION OF THE SATELLITE VELOCITY


118:  When a person stands on a scale in an elevator at rest, the scale reads 800 newtons.  When the elevator is allowed to fall freely with acceleration of gravity, the scale reads one of the following. Does the scale read?

w) 1600 Newton’s
x) 800 Newton’s
y) 400 Newton's
z) 0 Newton's

ANSWER:  Z -- 0 NEWTONS


119:  A 10,000-watt motor operates an elevator weighing 5000 Newton’s. Assuming no frictional losses, how high is the elevator raised in 10 seconds.  Is it raised?

w) 2 meters
x) 20 meters
y) 50 meters
z) 100 meters

ANSWER:  X -- 20 METERS


120:  A machine's output is 4000 joules and its frictional losses are 1000 joules.  Which of the following is its efficiency?  Is it:

w) 25%
x) 30%
y) 75%
z) 80%

ANSWER:  Z -- 80%
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