According to the scientific method, how does a physicist formulate and objectively test hypotheses?
In the steps of the scientific method, what is the next step after formulating and objectively testing hypotheses?
A hiker uses a compass to navigate through the woods. Which area of physics does this involves?
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
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
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
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A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly.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
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?
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?
Suppose you take a trip that covers 180km and takes 3 hours to make. Your average speed is
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)
convert to m (x 1000) = 10,070 m to the east
-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?
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
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
Suppose the force of friction on a sliding object is 25 N. The force needed to maintain a constant velocity is
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?
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
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?
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?