PHY101

What is the acceleration of the ball during any of these time intervals?

-10m/s

What is the change in its velocity during this 1-s interval?

-10m/s

What is the change in velocity during this 1-s interval?

-10m/s

What is the acceleration of the ball at the moment the ball has zero velocity?

-10m/s^2

What is the change in velocity during the 2-s interval?

-20m/s

What is science?

-Science creates testable laws and theories -Science is a way of knowing about the world and making sense of it. -Science describes the order in nature and the causes of that order.

An object in mechanical equilibrium is an object

-moving with no constant velocity -having no acceleration -at rest

An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration in meters per second per second is approximately

0

Two people each pull with 300 N on a rope in a tug of war. What is the net force on the rope?

0 N

What is the acceleration of a car that maintains a constant velocity of 100 km/h for 10 s?

0 km/h·s

The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant velocity is

10 N

What is the acceleration of a car moving along a straight road that increases its speed from 0 to 100 km/h in 10 s?

10 km/h·s

What is its velocity 1 s before it reaches its highest point?

10m/s

While you are in a bus that moves at 100 km/h you walk from the back to the front at 10 km/h. What is your speed relative to the road outside?

110 km/s

Suppose you are asked to find the area of a rectangle that is 2.1-cm wide by 5.6-cm long. Your calculator answer would be 11.76 cm2. Now suppose you are asked to enter the answer to two significant figures.

12 cm^2

How far does a horse travel if it gallops at an average speed of 25 km/h for 30 min?

12.5 km

A car accelerates at 2 meters per second per second. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 30 m/s?

15 seconds

If a projectile is fired straight up at a speed of 10 m/s, the total time to return to its starting position is about

2 seconds.

A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is

20 km/h

If a freely falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s/s, then its speed reading would increase each second by

20 m/s

If you pull horizontally on a crate with a force of 200 N, it slides across the floor in dynamic equilibrium. How much friction is acting on the crate?

200 N

Multiple-choice questions have a special grading rule determined by your instructor. Assume that your instructor has decided to grade these questions in the following way: If you submit an incorrect answer to a multiple-choice question with n options, you will lose 1/(n−1) of the credit for that question. Just like the similar multiple-choice penalty on most standardized tests, this rule is necessary to prevent random guessing.If a multiple-choice question has five answer choices and you submit one wrong answer before getting the question correct, how much credit will you lose for that part of the question?

25%

What is the average speed in kilometers per hour of a horse that gallops a distance of 15 km in a time of 30 min?

30 km/h

How much force is exerted on each person by the rope?

300 N

Ten seconds after starting from rest, a car is moving at 40 m/s. What is the car's acceleration in meters per second per second?

4.0

A 400 kg bear grasping a vertical tree slides down at constant velocity. What is the friction force that acts on the bear?

4000 N

If the strong man exerts a downward force of 800 N on the rope, how much upward force is exerted on the block?

800 N

Distinguish between a hypothesis and a theory.

A hypothesis is an educated guess, whereas a theory encompasses well tested and verified hypotheses.

What is the test for whether a hypothesis is scientific or not?

A hypothesis is scientific if it is possible to prove it wrong.

What exactly is meant by a "freely falling" object?

An object in free fall falls under gravity alone with no friction.

(Diameter×(57.3 degrees))Distance=

Angular Diameter

From fastest to slowest, rank the speeds of the balls 1 s after being thrown.

Ball C: 1m/s ; 3.1 kg Ball A: 4m/s ; 1.9kg Ball B: 6m/s ; 2.1 kg

What is the role of equations in this book?

Equations are guides to thinking and show connections between concepts.

Consider a pair of forces, one having a magnitude of 20 N and the other a magnitude of 12 N. What maximum net force is possible for these two forces?

Fmax = 32N

What is the minimum net force possible?

Fmin = 8 N

Why does the distance traveled by the ball in each half second after it is released change in the way in which it does?

Gravity is pulling down on the ball, so it accelerates down at a steady rate.

What are steps of the scientific method.

Hypothesis, predictions, and experimental findings

A block of mass 2kg is acted upon by two forces: 3N (directed to the left) and 4N (directed to the right). What can you say about the block's motion?

It could be moving to the left, moving to the right, or be instantaneously at rest.

What is the distance fallen for a freely falling object 1 s after being dropped from a rest position? What is the distance for a 4-s drop?

It falls 5 m in 1 s and 80 m in 4 s.

What is the acceleration of the ball when it is moving up, when it is at the maximum height, and when it is moving down?

It is always negative.

Why are students of the arts encouraged to learn about science and science students encouraged to learn about the arts?

Knowing both the arts and sciences makes for a wholeness in the way we view the world.

How many squares are in this 2×2 grid (Figure 1)? Note that the figure link lets you know that a figure goes along with this part. This figure is available to the left

Number of squares = 5

What test can you perform to increase the chance in your own mind that you are right about a particular idea?

See if you can state the objections of your opponents to their satisfaction.

Which is normally greater: static friction or sliding friction on the same object?

Static friction is normally greater than dynamic friction.

A different scaffold that weighs 400 N supports two painters, one 500 N and the other 400 N. The reading in the left scale is 800 N. What is the reading in the right-hand scale?

T= 500 N

Why did Aristarchus choose the time of a half Moon to make his measurements for calculating the Earth -Sun distance?

The Earth, Moon, and Sun formed a right triangle at that time.

Earth, like everything else illuminated by the Sun, casts a shadow. Why does this shadow taper?

The Sun is much larger than the Earth.

When you push horizontally on a crate that doesn't slide on a level floor, how great is the force of friction on the crate?

The friction force is equal and opposite to your push.

An object cannot remain at rest unless which of the following holds?

The net force acting on it is zero.

If a block is moving to the left at a constant velocity, what can one conclude?

The net force applied to the block is zero.

What is the speed acquired by a freely falling object 5 s after being dropped from a rest position? What is the speed 6 s after?

The speed is 50 m/s after 5 s and 60 m/s after 6 s.

What is the main difference between speed and velocity?

Velocity includes a direction, but speed does not.

Henry Heavyweight weighs 1300 N and stands on a pair of bathroom scales so that one scale reads twice as much as the other. What are the scale readings?

W1,W2 = 867,433 N

The sketch shows a painter's scaffold in mechanical equilibrium. The person in the middle weighs 500 N, and the tensions in each rope are 400 N. What is the weight of the scaffold?

W= 300 N

Lucy Lightfoot stands with one foot on one bathroom scale and her other foot on a second bathroom scale. Each scale reads 380 N . What is Lucy's weight?

W= 760 N

In daily life, people are often praised for maintaining some particular point of view, for the "courage of their convictions." A change of mind is seen as a sign of weakness. How is this different in science?

When a scientist finds evidence that contradicts a law, then the law must be abandoned.

The statement, "There are regions beneath Earth's crust that will always be beyond the reach of scientific investigation" is

a speculation

On a distant planet, a freely falling object gains speed at a steady rate of 12 m/s during each second of fall. Calculate its acceleration.

a= 12m/s^2

Consider the Moon and Sun. Their angular diameters are both equal to about .5 degree. If the Sun is roughly 400 times more distant than the Moon, how much bigger is the Sun's diameter than the Moon's?

about 400 times bigger

Galileo discovered that when air resistance can be neglected, all objects fall with the same ______.

acceleration

Hang from a pair of gym rings and the upward support forces of the rings will always

add up to equal your weight.

When you stand at rest on a pair of bathroom scales, the readings on the scales will always

add up to equal your weight.

A fact in science is ______.

an agreement between trained investigators

Facts in the field of science

are changeable

How can you use the graph of velocity versus time to estimate the acceleration of the ball?

by estimating the value of the slope of the graph

Which of the following is a scientific statement?

candy Bon Bons contain no sugar

Two forces, of magnitude 4N and 10N, are applied to an object. The relative direction of the forces is unknown. The net force acting on the object __________.

cannot have a magnitude equal to 5N

If an object moves with constant acceleration, its velocity must

change by the same amount each second

Calculate the vertical distance an object dropped from rest covers in 14 s of free fall.

d= 980 m

As the distance to the object increases, paralla

decreases

A truck is moving at constant velocity. Inside the storage compartment, a rock is dropped from the midpoint of the ceiling and strikes the floor below. The rock hits the floor

exactly below the midpoint of the ceiling.

Whereas Aristotle relied on logic in explaining nature, Galileo relied on

experiment

If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be

greater than the second before.

As the size of baseline increases, parallax

increases

As a skydiver gains speed in falling through the air, air resistance _______.

increases.

If your automobile runs out of fuel while you are driving, the engine stops but you do not come to an abrupt stop. The concept that most explains why is

inertia

What kind of speed is registered by an automobile speedometer?

instantaneous speed

Air resistance on a parachutist at terminal speed _______.

is greater for a heavier person

How does the distance traveled by the ball in the second half second compare with the distance traveled by the ball in the first half second?

it increases

What is the value of the velocity of the ball when it reaches its maximum height?

it is always zero

What is the magic number? (Figure 2) Note that there is a figure also associated with this part. However, the figure for Part A may still be visible on the left. To view the figure associated with Part B, click on the figure link. A new figure should appear on the left.

magic number = 60

Twelve seconds after starting from rest, an object falling freely will have a speed of

more than 100 m/s

A massive block is being pulled along a horizontal frictionless surface by a constant horizontal force. The block must be __________.

moving with a constant nonzero acceleration

Since an object weighs less on the surface of the Moon than on Earth's surface, does it have less inertia on the Moon's surface?

no

When a rocket ship accelerating in outer space runs out of fuel, it

no longer accelerates.

A force of gravity pulls downward on a book on a table. What force prevents the book from accelerating downward?

normal

The direction of the force of friction on a sliding crate is _______.

opposite to the direction of sliding

As the distance to background objects increases, parallax

remains the same

Use d=1/2gt2 and solve for the time one spends moving upward in a 0.6-m vertical jump. Then double it for the "hang time"-the time one's feet are off the ground.

t=0.7 s

A 1-kg stone and a 10-kg stone have the same acceleration in free fall because _______.

the ratio of weight to mass is the same for each.

A ball is thrown upwards and returns to the same position. Compared with its original speed after release, its speed when it returns is about

the same

Galileo's definition of speed was a breakthrough because he is acknowledged to be the first to consider ______.

time

A ball is tossed with enough speed straight up so that it is in the air several seconds. Assume upward direction is positive and downward is negative. What is the velocity of the ball when it reaches its highest point?

v= 0m/s

Calculate the instantaneous speed of an apple that falls freely from a rest position and accelerates at 10 m/s2 for 1.0 s

v= 10 m/s

Calculate the instantaneous speed (in m/s) at the 15-second mark for a car that accelerates at 1.4 m/s2 from a position of rest.

v= 21 m/s

A skydiver steps from a high-flying helicopter. In the absence of air resistance, how fast would she be falling at the end of a 12-s jump?

v=120m/s

A crate sits at rest on a factory floor. Friction between the crate and floor occurs _______.

when the crate is pushed horizontally, whether sliding or not.

A scientific hypothesis deemed valid must have a test for proving it ______.

wrong

A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is

zero

A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is

zero