Physics Ch 3

C

A car travels along west and its velocity decreases. The acceleration of the car is in which of the following directions? A. Westward B. Northward C. Eastward D. Southward

45 degrees

A certain vector has x and y components that are equal in magnitude. Which of the following is a possible angle for this vector in a standard x-y coordinate system?

D

A physics student adds two displacement vectors with magnitudes of 6.0 km and 4.0 km. Which of the following statements is true concerning the magnitude of the displacement? A. It must be 2.0 km. B. It could have any value between 2.0 km and 7.2 km depending on how the vectors are oriented. C. It must be 10 km. D. It could have any value between 2.0 km and 10.0 km depending on how the vectors are oriented.

A

A vector has components Ax = 12.0 m and Ay= 5.00 m. What is the angle that vector A makes with the x-axis? A. 22.6 degrees B. 32.6 degrees C. 12.6 degrees D. 67.4 degrees

C

A vector has components Ax = 9.0 m and Ay = 5.0 m. What is the magnitude of vector A? A. 106m B. 4m C. 10.3m D. 14m

B

At one point during the Tour de France bicycle race, three racers are riding along a straight, level section of road. The velocity of racer A relative to racer B is vAB; the velocity of A relative to C is vAC; and the velocity of C relative to B is vCB. If vAC = +4.0 m/s, and vCB = +2.0 m/s, what is vAB? A. 8 m/s B. 6 m/s C. -2 m/s D. 2 m/s

displacement, velocity, force

Give some examples of vectors.

C

Given that A + B = C, and that lAl^2 + lBl^2 = lCl^2, how are vectors A and B oriented with respect to each other? A. they are parallel and in the same direction B. they can be at any angle to each other C. they are perpendicular to each other D. they are at 45o to each other

Parallel and in the same direction

Given that A+B= C, and that lAl+lBl=lCl, how are vectors A and B oriented with respect to each other?

1st subscript refers to the object moving, second refers to the object relative to which the velocity is measured

How are subscripts ordered when referring to relative velocity?

by an arrow; length of the arrow indicates magnitude and direction is indicated by the "head" of the arrow

How is a vector represented?

D

If each component of a vector is halved, what happens to the angle of that vector? A. it doubles. B. it increases, but by less than double. C. it is reduced by half D. it does not change.

same magnitude, opposite direction

If two vectors are given such that A+B= 0, what can you say about the magnitude and direction of vectors A and B?

A

Vector A is along the x-axis and vector B is along the y-axis. Which of the following statements must be true? A. Vector A does not have any component along the y-axis and vector B does not have any component along the x-axis. B. The y-component of vector A is equal to the y-component of vector B. C. The x-component of vector A is equal and opposite to the y-component of vector B. D. The x-component of vector A is equal to the x-component of vector B.

A

Vector A is initially pointing northward. This vector is rotated counterclockwise by an angle of 110o. Which of the following statements is correct regarding the final position of vector A? A. It is pointing 20° south of west. B. It is pointing 20° west of north. C. It is pointing 70° south of east. D. It is pointing 70° east of south.

A

Vector r has a magnitude of 75 km/h and is directed at 25o relative to the x axis. Which of the following choices indicates the horizontal and vertical components of vector r? A. rx = +68 km/h, ry = 32 km/h B. rx = 37 km/h, ry = 68 km/h C. rx = 32 km/h, ry = 68 km/h D. rx = +187 km/h, ry = 87 km/h

mass, temperature, speed

What are some examples of scalars?

any vector can be moved parallel to its original direction as long as its length is unchanged

What are the rules of vectors?

D

Which of the following statements concerning vectors and scalars is true? A. Two vectors are equal only if they have the same magnitude and direction. B. A scalar (like temperature, not a scalar component, like speed)) can be either positive or negative. C. In calculations, the vector components of a vector may be used in place of the vector itself. D. All of the above

D

Which of the following statements is a true statement? A. A vector's magnitude cannot be more than the magnitude of one of its components. B. If the x-component of a vector is smaller than its y-component then that vector is in the opposite direction to its y-component. C. A vector's magnitude cannot be less than the sum of the magnitude of its components. D. The magnitude of a vector cannot be zero unless all of its components are zero.

B

Which one of the following statements concerning vectors and scalars is false? A. Two vectors are equal only if they have the same magnitude and direction. B. A vector that is zero may have components other than zero. C. In calculations, the vector components of a vector may be used in place of the vector itself. D. The vector components, Ax and Ay, may be either positive or negative but the scalar components, Ax and Ay, can only be positive.

C

You are trying to cross a river that flows due south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat... A. due north B. in a SW direction C. in a NW direction D. due south

frame of reference

a coordinate system plus a time scale

vector

a number with magnitude and direction

scalar

a simple number with units; magnitude

unit vector

a vector with a magnitude of 1 that gives direction; uses the x and y direction

the relative velocity

velocity of a body seen by an observer