Physics Exam 1

What is the minimum number of vectors with equal magnitudes whose vector sum can be zero? (a) two (b) three (c) four (d) five (e) six

(a) two

Complete the following statement: Today, the standard meter is defined in terms of a) the distance from the earth's equator to the north pole b) the wavelength of light emitted from a krypton atom c) the wavelength of light emitted from a sodium atom d) a platinum-iridium bar kept in France e) the speed of light

e) the speed of light

A ball is thrown vertically upward from the surface of the earth. Consider the following quantities: (1) the speed of the ball; (2) the velocity of the ball; (3) the acceleration of the ball. Which of these is (are) zero when the ball has reached the maximum height? (a) 1 and 2 only (c) 1 only (e) 1, 2, and 3 (b) 1 and 3 only (d) 2 only

(a) 1 and 2 only

Two vectors A and B are added together to form a vector C. The relationship between the magnitudes of the vectors is given by: A^2 + B^2 = C^2 . Which statement concerning these vectors is true? (a) A and B must be at right angles to each other. (b) A and B could have any orientation relative to each other. (c) A and B must have equal lengths. (d) A and B must be parallel. (e) A and B could be antiparallel.

(a) A and B must be at right angles to each other.

In which one of the following cases is the displacement of the object directly proportional to the elapsed time? (a) a ball rolls with constant velocity (b) a ball at rest is given a constant acceleration (c) a ball rolling with velocity v 0 is given a constant acceleration (d) a bead falling through oil experiences a decreasing acceleration (e) a rocket fired from the earth's surface experiences an increasing acceleration

(a) a ball rolls with constant velocity

Complete the following statement: Today, the standard unit of time is defined in terms of (a) the electromagnetic waves emitted by cesium atoms. (b) the motion of the moon around the earth. (c) the motion of a precision pendulum. (d) the average solar day. (e) the speed of light.

(a) the electromagnetic waves emitted by cesium atoms.

For which one of the following situations will the path length equal the magnitude of the displacement? (a) A jogger is running around a circular path. (b) A ball is rolling down an inclined plane. (c) A train travels 5 miles east before it stops. It then travels 2 miles west. (d) A ball rises and falls after being thrown straight up from the earth's surface. (e) A ball on the end of a string is moving in a vertical circle.

(b) A ball is rolling down an inclined plane.

Three vectors A, B, and C add together to yield zero: A + B + C = 0. The vectors A and C point in opposite directions and their magnitudes are related by the expression: A = 2C. Which one of the following conclusions is correct? (a) A and B have equal magnitudes and point in opposite directions. (b) B and C have equal magnitudes and point in the same direction. (c) B and C have equal magnitudes and point in opposite directions. (d) A and B point in the same direction, but A has twice the magnitude of B. (e) B and C point in the same direction, but C has twice the magnitude of B.

(b) B and C have equal magnitudes and point in the same direction.

Two objects A and B accelerate from rest with the same constant acceleration. Object A accelerates for twice as much time as object B, however. Which one of the following statements is true concerning these objects at the end of their respective periods of acceleration? (a) Object A will travel twice as far as object B. (b) Object A will travel four times as far as object B. (c) Object A will travel eight times further than object B. (d) Object A will be moving four times faster than object B. (e) Object A will be moving eight times faster than object B.

(b) Object A will travel four times as far as object B.

A football is kicked at an angle with respect to the horizontal. Which one of the following statements best describes the acceleration of the football during this event if air resistance is neglected? (a) The acceleration is zero m/s 2 at all times. (b) The acceleration is 9.8 m/s 2 at all times. (c) The acceleration is zero m/s 2 when the football has reached the highest point in its trajectory. (d) The acceleration is positive as the football rises, and it is negative as the football falls. (e) The acceleration starts at 9.8 m/s 2 and drops to some constant lower value as the ball approaches the ground.

(b) The acceleration is 9.8 m/s 2 at all times.

A rock is thrown vertically upward from the surface of the earth. The rock rises to some maximum height and falls back toward the surface of the earth. Which one of the following statements concerning this situation is true if air resistance is neglected? (a) As the ball rises, its acceleration vector points upward. (b) The ball is a freely falling body for the duration of its flight. (c) The acceleration of the ball is zero when the ball is at its highest point. (d) The speed of the ball is negative while the ball falls back toward the earth. (e) The velocity and acceleration of the ball always point in the same direction.

(b) The ball is a freely falling body for the duration of its flight.

Complete the following statement: Today, the standard unit of mass is defined in terms of (a) a specified volume of water at 4 °C. (b) a standard platinum-iridium cylinder. (c) a specified number of cesium atoms. (d) a standard platinum bar. (e) the speed of light.

(b) a standard platinum-iridium cylinder.

Which one of the following is not a vector quantity? (a) acceleration (b) average speed (c) displacement (d) average velocity (e) instantaneous velocity

(b) average speed

What is the minimum number of vectors with unequal magnitudes whose vector sum can be zero? (a) two (b) three (c) four (d) five (e) six

(b) three

Which one of the following statements concerning this car is true? (a) The displacement of the car does not change with time. (b) The instantaneous velocity of the car is constant. (c) The average speed of the car is the same over any time interval. (d) The average velocity of the car is the same over any time interval. (e) The average speed of the car over any time interval is equal to the magnitude of the average velocity over the same time interval.

(c) The average speed of the car is the same over any time interval.

Starting from rest, a particle confined to move along a straight line is accelerated at a rate of 5.0 m/s^2 . Which one of the following statements accurately describes the motion of this particle? (a) The particle travels 5.0 m during each second. (b) The particle travels 5.0 m only during the first second. (c) The speed of the particle increases by 5.0 m/s during each second. (d) The acceleration of the particle increases by 5.0 m/s 2 during each second. (e) The final speed of the particle will be proportional to the distance that the particle covers.

(c) The speed of the particle increases by 5.0 m/s during each second.

A bicyclist is riding at a constant speed along a straight-line path. The rider throws a ball straight up to a height a few meters above her head. Ignoring air resistance, where will the ball land? (a) behind the rider (b) in front of the rider (c) in the same hand that threw the ball (d) in the opposite hand to the one that threw it (e) This cannot be determined without knowing the speed of the rider and the maximum height of the ball.

(c) in the same hand that threw the ball

A particle travels along a curved path between two points P and Q as shown. The displacement of the particle does not depend on (a) the location of P. (b) the location of Q. (c) the distance traveled from P to Q. (d) the shortest distance between P and Q. (e) the direction of Q from P.

(c) the distance traveled from P to Q.

Which one of the following quantities is a vector quantity? (a) the age of the earth (b) the mass of a freight train (c) the earth's pull on your body (d) the temperature of hot cup of coffee (e) the number of people attending a soccer game

(c) the earth's pull on your body

Two vectors A and B are added together to form a vector C. The relationship between the magnitudes of the vectors is given by A + B = C. Which one of the following statements concerning these vectors is true? (a) A and B must be displacements. (b) A and B must have equal lengths. (c) A and B must point in opposite directions. (d) A and B must point in the same direction. (e) A and B must be at right angles to each other.

(d) A and B must point in the same direction.

Which one of the following situations is not possible? (a) A body has zero velocity and non-zero acceleration. (b) A body travels with a northward velocity and a northward acceleration. (c) A body travels with a northward velocity and a southward acceleration. (d) A body travels with a constant velocity and a time-varying acceleration. (e) A body travels with a constant acceleration and a time-varying velocity.

(d) A body travels with a constant velocity and a time-varying acceleration.

Which one of the following statements concerning vectors and scalars is false? (a) In calculations, the vector components of a vector may be used in place of the vector itself. (b) It is possible to use vector components that are not perpendicular. (c) A scalar component may be either positive or negative. (d) A vector that is zero may have components other than zero. (e) Two vectors are equal only if they have the same magnitude and direction.

(d) A vector that is zero may have components other than zero.

Ball A is dropped from rest from a window. At the same instant, ball B is thrown downward; and ball C is thrown upward from the same window. Which statement concerning the balls after their release is necessarily true if air resistance is neglected? (a) At some instant after it is thrown, the acceleration of ball C is zero. (b) All three balls strike the ground at the same time. (c) All three balls have the same velocity at any instant. (d) All three balls have the same acceleration at any instant. (e) All three balls reach the ground with the same velocity.

(d) All three balls have the same acceleration at any instant.

In which one of the following situations does the car have a westward acceleration? (a) The car travels westward at constant speed. (b) The car travels eastward and speeds up. (c) The car travels westward and slows down. (d) The car travels eastward and slows down. (e) The car starts from rest and moves toward the east.

(d) The car travels eastward and slows down.

An object moving along a straight line is decelerating. Which one of the following statements concerning the object's acceleration is necessarily true? (a) The value of the acceleration is positive. (b) The direction of the acceleration is in the same direction as the displacement. (c) An object that is decelerating has a negative acceleration. (d) The direction of the acceleration is in the direction opposite to that of the velocity. (e) The acceleration changes as the object moves along the line.

(d) The direction of the acceleration is in the direction opposite to that of the velocity.

A baseball is hit upward and travels along a parabolic arc before it strikes the ground. Which one of the following statements is necessarily true? (a) The acceleration of the ball decreases as the ball moves upward. (b) The velocity of the ball is zero m/s when the ball is at the highest point in the arc. (c) The acceleration of the ball is zero m/s 2 when the ball is at the highest point in the arc. (d) The x-component of the velocity of the ball is the same throughout the ball's flight. (e) The velocity of the ball is a maximum when the ball is at the highest point in the arc.

(d) The x-component of the velocity of the ball is the same throughout the ball's flight.

28. Which one of the following statements must be true if the expression x=v0t + 1/2 at^2 is to be used? (a) x is constant. (b) v is constant. (c) t is constant. (d) a is constant. (e) Both v0 and t are constant.

(d) a is constant.

Which one of the following choices is a vector quantity? (a) mass (b) temperature (c) time (d) displacement (e) volume

(d) displacement

Two cars travel along a level highway. It is observed that the distance between the cars is increasing. Which one of the following statements concerning this situation is necessarily true? (a) The velocity of each car is increasing. (b) At least one of the cars has a non-zero acceleration. (c) The leading car has the greater acceleration. (d) The trailing car has the smaller acceleration. (e) Both cars could be accelerating at the same rate.

(e) Both cars could be accelerating at the same rate.

A physics student adds two displacement vectors with magnitudes of 8.0 km and 6.0 km. Which one of the following statements is true concerning the magnitude of the resultant displacement? (a) It must be 10.0 km. (b) It must be 14.0 km. (c) It could be equal to zero kilometers, depending on how the vectors are oriented. (d) No conclusion can be reached without knowing the directions of the vectors. (e) It could have any value between 2.0 km and 14.0 km depending on how the vectors are oriented.

(e) It could have any value between 2.0 km and 14.0 km depending on how the vectors are oriented.

Which one of the following statements is true concerning scalar quantities? (a) Scalar quantities must be represented by base units. (b) Scalar quantities have both magnitude and direction. (c) Scalar quantities can be added to vector quantities using rules of trigonometry. (d) Scalar quantities can be added to other scalar quantities using rules of trigonometry. (e) Scalar quantities can be added to other scalar quantities using rules of ordinary addition.

(e) Scalar quantities can be added to other scalar quantities using rules of ordinary addition.

Which one of the following is an SI base unit? a) gram b) slug c) newton d) centimeter e) kilogram

e) kilogram