Test One

An object moves from x = -2.1 m, y = 3.7 m, z = 1.4 m to x = 3.3 m, y = -1.1 m, z = 4.2 m in a time of 5.3 s. What is its average velocity?

(1.0 m/s)i − (0.91 m/s)j + (0.53 m/s)k

One metric second equals how many normal seconds?

.864

The value of k * (k x i) is:

0

A particle is located at coordinates (2 m, 6 m, 8 m). What is the y component of the particle's position vector, measured from the origin?

6m

Let vector V = 2.00i + 6.00j - 3.00k. The magnitude of Vis:

7

A 90-kg man stands in an elevator that has a downward acceleration of 1.4 m/s2. The force exerted by him on the floor is about:

760 N

Vectors A and B lie in the xy plane. We can deduce that A = B if:

Ax = Bx and Ay = By

Which of the following is true, according to Newton's second law?

The acceleration of an object is proportional to the net force on it and inversely proportional to its mass.

On a plot of a particle's acceleration versus time, which of the following is related to the velocity?

area between the plot and the time axis

There is no SI base unit for area because:

area can be expressed in terms of square meters

At what point during the flight of a projectile is the projectile's speed least?

at maximum height

A particle moves along an x axis from the origin of the x axis to x = 15 m and then back to x = 5 m, all in 30 s. Which of the following depends on the total distance it moves?

average speed

Which unit vector points in the positive direction of the z axis?

k

The SI base unit for mass is:

kilogram (kg)

If a particle's velocity is in the positive direction along an x axis as the speed increases at a constant rate, which of the following describes a plot of its acceleration versus time?

plot has zero slope

A ball is in free fall motion. Upward is taken to be the positive direction. The displacement of the ball is:

positive during ascent and negative during descent

Which of the following is equal to the period in uniform circular motion?

ratio of the circumference to the speed

The inertia of a body tends to cause the body to:

resist any change in its motion

If a particle moves with velocity vPA→ = (2.0 m/s) i^ + (4.0 m/s) j^ relative to frame A, what is the velocity vAP→ of the frame relative to the particle?

-(2.0 m/s)i - (4.0 m/s)j

f a particle moves with velocity vPA→ = (2.0 m/s) i^ relative to reference frame A, what is the velocity vAP→ of the frame relative to the particle?

-2.0 m/s i

This graph shows the position of a particle as a function of time. What is its average velocity between t = 5s and t = 9s? couldn't add pic but- line goes downward from x(m) = 12 to x(m) = 0. so 12/4 = 3 going downward = ?

-3 m/s

For the vectors d→ = -4.0 i + 3.0 j - 5.0 k and b→ = 3.0 i -2.0 j - 2.0 k, what is the net y component?

1.0

A ball with a weight of 1.5 N is thrown at an angle of 30° above the horizontal with an initial speed of 12 m/s. At its highest point, the net force on the ball is:

1.5 N, down

what is the meaning of the prefix micro- ?

10^-6

A plane traveling north at 200 m/s turns and then travels south at 200 m/s. The change in its velocity is:

400 m/s

A sphere has a radius of 21 cm and a mass of 1.9 kg. Its mass density is about:

49 kg/m3

If 1 u = 1.66 x 10-27 kg, 1 gram =

6.02 x 10^23 u

If vectors A→ and B→ are parallel, which product gives zero?

Cross Product of the two vectors

If vectors A→ and B→ are perpidicular, which product gives zero?

Dot product of the two vectors

What is the relationship between instantaneous speed and instantaneous velocity?

Instantaneous speed is the magnitude of the instantaneous velocity.

The position y of a particle moving along the y axis depends on the time t according to the equation y = at - bt2. The dimensions of the quantities a and b are respectively:

L/T, L/T^2

Suppose A = BC, where A has the dimensions L/M and C has the dimensions L/T. Then B has the dimension:

T/M

A box is on a scale. In which of these situations will the scale reading NOT equal the weight of the box?

The scale and box are on a steep slope, held in place by friction.

Volume of a sphere

V=4/3πr³

Is the vector addition g→ + h→ the same as the vector addition h→ + g→ ?

Yes

Can an object have positive acceleration and decreasing speed?

Yes, this is possible if the initial velocity is negative.

To get a particle's change in velocity, which of the following should be integrated with respect to time?

acceleration function

A lead block is suspended from your hand by a string. The reaction to the force of gravity on the block is the force exerted by the:

block on the Earth

Which type of product gives a vector as a result?

cross product

A block is accelerated by a single force. If the magnitude of the force is doubled, what happens to the magnitude of the acceleration?

doubled

An object moving at constant velocity in an inertial frame must:

have zero net force acting on it

The vector -A (with arrow on top) is:

in the direction opposite to A (with an arrow on top)

Two blocks with masses m and M are pushed along a horizontal frictionless surface by a horizontal applied force F→ as shown. The magnitude of the force of either of these blocks on the other is:

mF/(m + M)

If a vector is multiplied by a positive scalar, such as +3, does its direction change?

no

The SI standard of time is based on:

none of these: daily rotation of the earth, frequency of light emitted by Kr86, yearly revolution of earth about sun, precision pendulum clock

What is the direction of the result of the cross product of vectors A→ and B→?

perpendicular to the plane of vectors A and B

If a particle's velocity is in the positive direction along an x axis as the speed decreases at a constant rate, which of the following describes a plot of its acceleration versus time?

plot has zero slope

A feather and a lead ball are dropped from rest in vacuum on the Moon. The acceleration of the feather is:

the same as that of the lead ball

The "reaction" force does not cancel the "action" force because:

they act on different bodies

If you stand on a floor, how does the normal force on you compare to your weight?

they are equal

A heavy steel ball B is suspended by a cord from a block of wood W. The entire system is dropped through the air. Neglecting air resistance, the tension in the cord is:

zero