PHYSICS 1 - midterm 1 review

If an equation is dimensionally correct, does that mean that the equation must be true?

No

If an equation is not dimensionally correct, does that mean that the equation cannot be true?

Yes

Must two quantities have the same dimensions if you are adding them?

Yes

Must two quantities have the same dimensions if you are multiplying them?

No

Must two quantities have the same dimensions if you are subtracting them?

Yes

Must two quantities have the same dimensions if you are equating them?

Yes

Newton's second law of motion says that the mass of an object times its acceleration is equal to the net force on the object. Which of the following gives the correct units for force?

kgm/ s^2

The fundamental quantity is

temperature

torr is the unit of

pressure

Which of the following is the dimensions of pressure?

[ML-1T-2]

Dimensions of Gravitational constant G are

[M-1L3T-2]

density of an object is defined as

the amount of mass for each unit of volume

The equation for the change of position of a train starting at t=0 is given by ____, where a and b are constants. What is the dimension of b? Note that a and b are constant with dimensions.

LT-3

Which one of the quantities below has dimensions equal to [ML/T^2]

(mv^2)/r

if force F, acceleration A and time T are taken as fundamental physical quantities, the dimension of length L in this new system will be

[AT^2]

The distance between two cities is 100 mi. Is the number of kilometers between the two cities larger, smaller, or equal to 100?

larger than 100 D

Dimensional analysis cannot give you the numerical value of constants of proportionality that may appear in an algebraic expression

True

Under which of the following conditions is the magnitude of the average velocity of a particle moving in one dimension smaller than the average speed over some time interval?

a particle moves in the +x direction and then reverses the direction of its motion

If the average velocity of an object is zero in some time interval, displacement of the object in that time interval is

zero

members of the highway patrol are more interested in ______ as you drive

your instantaneous speed

If the displacement of a body is proportional to square of the time, then the body has

uniform acceleration

The displacement S of a particle along a straight line at time t is given by s=a+bt+ct^2 , where a,b, and c are constants. The acceleration of the particle is

2c

If a car is traveling eastward and slowing down, what is the direction of the force on the car that causes it to slow down?

westward

A student at the top of a building of height h throws one ball upward with a speed of Vi and then throws a second ball downwards with the same initial speed Vi. Just before it reaches the ground, is the final speed of the ball thrown upward

the same magnitude, compared with the final speed of the ball thrown downwards

A juggler throws a bowling pin straight up in the air. After the pin leaves his hand and while it is in the air, which statement is true?

the velocity of the pin is opposite its acceleration on the way up

What happens to the acceleration of a ball after it is thrown upward into the air

remains the same

what happens to the speed of a ball after it is thrown upward into the air

decreases and then increases

acceleration at highest point when a ball is projected from the ground is

downwards

The acceleration of a moving body can be obtained from

slope of the velocity-time graph

Distance moved by a uniformly accelerating body starting from rest in time t is proportional to

t^2

A body is thrown with speed 20 m/s vertically upward. It will return to throwers hand after a time (g=10 m/sec)

4 sec

which of the following are vector quantities

acceleration & velocity

if vector B is added to vector A, which two of the following choices must be true for the resultant vector to be equal to zero?

A and B are parallel and in opposite directions

A and B have the same magnitude

For which of the following vectors is the magnitude of the vector equal to one of the components of the vector

C= +5K

For the resultant of two vectors to be maximum, the angle between them should be

0 deg

what is the y component of the vector (3i-8k) m/s ?

0

the gradient of the temperature

has direction along which temperature increases

vector A lies in the xy plane. Both of its components will be negative if it lies in which quadrant?

the third quadrant

which of the following are scalar quantities

age, speed, mass

is force a vector?

yes

is temperature a vector?

no

Is the following quantity a vector ?

the volume of water in a can

no

Is the following quantity a vector?

Ratings of a TV show

no

Is the following quantity a vector?

height of a building

no

Is the following quantity a vector?

the velocity of a sports car

yes

Is the following quantity a vector?

The age of the Universe

no

A vector points from the origin into the second quadrant of the xy plane. What can you conclude about its components?

the x component is negative, and the y component is positive

A vector lying in the xy plane has components of opposite sign. The vector must lie in which quadrant?

either the second or the fourth quadrant

If the magnitude of sum of the two vector is equal to the magnitude of the difference between them, then the angle between the vectors is

90 deg

The resultant of two vectors A and B gets rotated through 90 deg if one of these vectors is reversed. Then these vectors must

be perpendicular

A component of a vector is _____ less or equal than the magnitude of the vector

always

In this situation is the moving object appropriately modeled as a projectile?

A shoe is tossed in an arbitrary direction

yes

In this situation is the moving object appropriately modeled as a projectile?

A jet airplane crosses the sky with its engines thrusting the plane forward.

no

In this situation is the moving object appropriately modeled as a projectile?

A rocket leaves the launch pad

no

In this situation is the moving object appropriately modeled as a projectile?

A diver throws a stone under water

no

A projectile is launched on the Earth with a certain initial velocity and moves without air resistance. Another projectile is launched with the same initial velocity on the Moon, where the acceleration due to gravity is one-sixth as large. How does the range of the projectile on the Moon compare with that of the projectile on the Earth?

6 times larger

a car moving around a circular track with constant speed has

an acceleration directed toward the center of its path

A rubber stopper on the end of a string is swung steadily in a horizontal circle. In one trial, it moves at speed v in a circle of radius r. In a second trial, it moves at a higher speed 3v in a circle of radius 3r. In this second trial, its acceleration is:

three times larger

A set of keys on the end of a string is swung steadily in a horizontal circle. In one trial, it moves at speed v in a circle of radius r. In a second trial, it moves at a higher speed 4v in a circle of radius 4r. In the second trial, how does the period of its motion compare with its period in the first trial?

it is the same as in the first trial

A student throws a heavy red ball horizontally from a balcony of a tall building with an initial speed v. At the same time, a second student drops a lighter blue ball from the balcony. Neglecting air resistance, which statement is true?

the balls reach the ground at the same instant

A baseball is thrown from the outfield toward the catcher. When the ball reaches its highest point, which statement is true?

Its velocity is perpendicular to its acceleration

Which of the following particles, if any, have an acceleration?

a particle moving around a curve with constant speed

As a projectile thrown upward moves in its parabolic path, at what point along its path are the velocity and acceleration vectors for the projectile perpendicular to each other?

the highest point

A particle moves along a path and its speed increases with time. In which of the following cases are its acceleration and velocity vectors parallel?

the path is straight

If you know the position vectors of a particle at two points along its path and also know the time it took to get from one point to the other, can you determine the particle's instantaneous velocity and average velocity? (Select all that apply.)

the average velocity can be determined

from the same choices, at what point are the velocity and acceleration vectors for the projectile parallel to each other?

nowhere

A particle moves along a path and its speed increases with time.From the same choices, in which case are its acceleration and velocity vectors perpendicular everywhere along the path?

never

the horizontal range of a projectile is 4 rad 3 times its maximum height, then the angle of projection will be

30 deg

the greatest height to which a man can throw is h. The greatest distance to which he can throw will be

2h

two particles of equal masses are revolving in circular paths of radii r1 and r2 respectively. If they experience equal centripetal forces, the ratio of their angular velocities is

rad (r2/r1)

In this situation is the moving object appropriately modeled as a projectile?A rocket moves through the sky, at much less than the speed of sound, after its fuel has been used up.

yes

Which of the following is correct?

a. It is possible for an object to have motion in the absence of forces on the object.

b. It is possible to have forces on an object in the absence of motion of the object

c. neither 1 nor 2 is correct

d. both 1 and 2 are correct

both 1 and 2 is correct

an object experiences no acceleration. which of the following cannot be true for the object

a single force acts on the object

Suppose you are talking by interplanetary telephone to a friend, who lives on the Moon. He tells you that he has just won a newton of gold in a contest. Excitedly, you tell him that you entered the Earth version of the same contest and also won a newton of gold! Who is richer?

your friend is

if a fly collides with the windshield of a fast-moving bus, which experiences an impact force with a larger magnitude?

the same force is experienced by both

If a fly collides with the windshield of a fast-moving bus, which experiences the greater acceleration?

the fly

The manager of a department store is pushing horizontally with a force of magnitude 200 N on a box of shirts. The box is sliding across the horizontal floor with a forward acceleration. Nothing else touches the box. What must be true about the magnitude of the force of kinetic friction acting on the box?

it is less than 200N

A rubber ball is dropped onto the floor. What force causes the ball to bounce?

reaction force of the floor

A truck loaded with sand accelerates along a highway. The driving force on the truck remains constant. What happens to the acceleration of the truck if its trailer leaks sand at a constant rate through a hole in its bottom?

it increases at a steady rate

An object of mass m is sliding with speed at some instant across a level tabletop, with which its coefficient of kinetic friction is μ. It then moves through a distance d and comes to rest. Which of the following equations for the speed is reasonable?

vi = rad (2ugd)

what is inertia ?

the tendency of an object to continue doing what it is currently doing

frictional force is always proportional to

normal reaction

when a bus starts suddenly, the supper part of sitting passenger experiences a sudden motion in backward direction due to

inertia of rest

an athlete runs some distance before taking a long jump because

by running the athlete gives himself larger inertia of motion

You push an object, initially at rest, across a frictionless floor with a constant force for a time interval Δt, resulting in a final speed of v for the object. You then repeat the experiment, but with a force that is twice as large. What time interval is now required to reach the same final speed v?

delta t / 2

You are playing with your daughter in the snow. She sits on a sled and asks you to slide her across a flat, horizontal field. Which choice below would be easier for you?

attaching a rope to the front of the sled and pulling with a force at 30 deg above the horizontal

what is the ratio of the linear velocities for the point of the minute and hour hands of a clock if the minute hand is 1.5 times longer than the hour hand?

18

describe the path of a moving body in the event that its acceleration is constant in magnitude at all times and perpendicular to the velocity

the object will move in a circle at a constant speed

describe the path of a moving body in the event that its acceleration is constant in magnitude at all times and parallel the velocity

the object will move in a straight line at a changing speed

a cyclist in an Olympic race is moving in a circular track of radius 80m with speed 72km/h. He has to lean from the vertical approximately through an angle

tan -1 (1/2)

The driver of a speeding empty truck slams on the brakes and skids to a stop through a distance d. If the truck now carries a load that doubles its mass, what will be the truck's "skidding distance"?

d

railway tracks are banked on curves

for providing necessary centripetal force from the horizontal component of normal reaction on the track

As a raindrop falls through the atmosphere, its speed initially changes as it falls toward the Earth. Before the raindrop reaches its terminal speed, does the magnitude of its acceleration

decreases

Consider a skydiver who has stepped from a helicopter and is falling through air, before she reaches terminal speed and long before she opens her parachute. Does her speed:

increases

resultant of two forces of equal magnitude acting at right angle is 1414 N, the magnitude of either force is

1000

A baseball and a basketball, having the same mass, are dropped through air from rest such that their bottoms are initially at the same height above the ground, on the order of 10 m or more. Which one strikes the ground first? (consider air resistance)

baseball strikes the ground first

A man swings a bucket of water in a vertical circle of diameter 2m. The minimum speed with which he must swing the bucket so that the water does not spill out of the bucket is

3.13