## 80 terms

### According to the scientific method, how does a physicist formulate and objectively test hypotheses?

by experiments

### In the steps of the scientific method, what is the next step after formulating and objectively testing hypotheses?

interpreting results

### A hiker uses a compass to navigate through the woods. Which area of physics does this involves?

electromagnetism

### What two dimensions, in addition to mass, are commonly used by physicists to derive additional measurements?

length and time

### How does a scientist reduce the frequency of human error and minimize a lack of accuracy?

take repeated measurements

use the same method of measurement

maintain instruments in good working order

### Three values were obtained for the mass of a metal bar: 8.83 g; 8.84 g; 8.82 g. The known mass is 10.68. The values are

precise

### Calculate the following, and express the answer in scientific notation with the correct number of significant figures: 21.4+15+17.17+4.003

5.8 x 10^1

(the number with the lowest amount of sig figs is 15, which has two sig figs so the answer must have 2 sig figs)

### Calculate the following, and express the answer with the correct number of significant figures: 1.23 x 0.89

1.1

### What is not a step that is part of the scientific method?

Repeat the experiments until the answers match the predictions (doesn't have to match your predictions)

### One difference between a hypothesis and a theory is that a hypothesis

is a guess that has not been well tested, whereas a theory is a synthesis of well-tested guesses

### What is an example of a scientific hypothesis?

Atoms are the smallest particles of matter that exist (If it is a valid hypothesis, there must be a test for proving that it is wrong)

### A human hair is approximately 50 micrometers in diameter. Express this is meters.

5.0 x 10^-5 m

(50micrometers x 1x10^-6m/1micrometer = 50 x 10^6 = 5.0 x10^-5)

### When a hypothesis has been tested over and over again and has not been contradicted, it may become a

law

### physics is the most basic science because

it is about the nature of basic things like forces, energy, and motion

### The law of inertia states that an object

-will continue moving at the same velocity unless an outside force acts on it

-will continue moving in a straight line unless an outside force acts on it

-that is not moving will never move unless a force acts on it

-at rest will remain at rest unless acted on by an outside force

### A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. The reason this can be done is that

the milk carton has inertia

### According to Newton's law of inertia, a railroad in motion should continue going forever even if its engine is turned off. We never observe this because railroad trains

always have forces that oppose their motion

### How does acceleration of an object change in relation to the applied force? It is

directly proportional

### Suppose a cart is being moved by a force. If suddenly a load is dumped into the cart so that the cart's mass doubles, what happens to the cart's acceleration?

It halves

### How much force is needed to accelerate a 4.0 kg physics book to an acceleration of 2.0 m/s^2?

8.0 N

### If shopping cart A has five times more mass in it than shopping cart B and the two cars are pushed with equal forces, you can expect the acceleration of shopping cart A to be

1/5 times that of shopping cart B

### What statements describe force?

-force causes objects to start moving

-force causes objects to stop moving

-force causes objects to change direction

### A net force of 6.8 N accelerates a 31 kg scooter across a level parking lot. What is the magnitude of the scooter's acceleration?

0.22 m/s^2

### Suppose you take a trip that covers 180km and takes 3 hours to make. Your average speed is

60 km/h

(x/t=speed)

(180km/3h=60km/h)

### A school bus takes 0.530h to reach the school from your house. If the average velocity is 19km/h to the east, what is the displacement?

(average velocity=change in x/ change in t)

(19=change in x/ 0.530)

19x.530=10.07 km

convert to m (x 1000) = 10,070 m to the east

### Speed is

-a measure of how fast something is moving

-always measured in terms of a unit of distance divided by a unit of time

-the distance covered per unit time

### A car accelerates at 2 m/s^2. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 20m/s?

10 seconds

### The motion of a ball on an inclined plane is described by the equation: change in x=1/2a(change in time)^2. Which of the following must have a value of zero?

initial velocity (vi)

### Suppose an object is in free fall. Each second the object falls

a larger distance than in the second before

### Would a leaf or a stone fall with greater acceleration in a vacuum?

they would accelerate at the same rate

### A baseball catcher throws a ball vertically upward and catches it in the same spot as it returns to the mitt. At what point in the ball's path does it experience zero velocity and nonzero acceleration at the same time?

at the top of its path

### At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?

Neither. They both hit the ground at the same time.

### Identify the following quantities as scalar or vector: the mass of an object, the number of leaves on a tree, wind velocity.

scalar, scalar, vector

### A ball thrown in the air will never go as far as physics ideally would predict because

air friction slows the ball

### In the absence of air resistance, the angle at which a thrown ball will go the farthest is

45 degrees

### What is the resultant of a 3-unit vector and a 4-unit vector at right angles to each other?

5 units

### A projectile is fired horizontally in a vacuum. The projectile maintains its horizontal component of speed because it

is not acted on by any horizontal forces

### A person is attracted towards the center of Earth by 440-N gravitational force. The force with which Earth is attracted toward the person is

440 N

### Suppose the force of friction on a sliding object is 25 N. The force needed to maintain a constant velocity is

25 N

### In a coordinate system, the magnitude of the x component of a vector and theta, the angle between the vector and x-axis, are known. The magnitude of the vector equals the x component

divided by the cosine of theta

### What is the name of the type of friction that opposes the movement of two surfaces that are in contact and are sliding over each other?

kinetic friction

### When representing velocity as a vector,

-the direction of the arrow shows the direction of motion

-the length of the arrow represents the speed

-the length of the arrow is drawn to a suitable scale

### The gravitational force b/w two massive spheres

-is always an attraction

-depends on how massive they are

-depends inversely on the square of the distance b/w them

### Two objects move toward each other b/c of gravitational attraction. As the objects get closer and closer, the force b/w them

increases

### Suppose the gravitational force b/w two massive spheres is 100N. If the distance b/w the spheres is doubled, what is the force b/w the masses?

25 N

### Suppose the gravitational force b/w two spheres is 30N. If the magnitude of each mass doubles, what is the force b/w the masses?

120 N

### The gravitational force b/w two masses is 36 N. What is the gravitational force if the distance b/w them is tripled?

4.0 N