Physical Science, Test#1
What is meant by 'pseudoscience?'
'fake science,' one that doesn't live up to scientific standards. (pretends to be a real science; ex: astrology-horoscopes)
List the steps of the classic scientific method.
1) Observe (identify a question/ puzzle/ unexplained observation,) 2) Question (form a hypothesis to answer the question,) 3) Predict (predict consequences that can be observed if the hypothesis is correct, or non-existent if the hypothesis is incorrect,) 4) Test predictions (do experiments,) 5) Conclusion (develop the simplest general rule that organizes the hypothesis, the predicted effects, & the experimental findings.
A 1-kg mass at Earth's surface weighs about
10N
A car moves 4 times as fast as another identical car. Compared with the slower car, the faster car has
16 times the kinetic energy
How much tension is there in a vertical rope that holds a 20N bag of apples at rest?
20N
What's the net force on a box pushed to the right with 50N of force, while being pushed to the left with 20N of force?
30N (and the box would move to the right)
A music console is pushed a distance of 2 m with a force of 20 N. The work done on the console is
40 J
Compare life before science and technology (in the good old days,) with life in the present time. Consider fields of medicine, transportation, and communication.
4k years ago, once science & math integrated, both science and the human condition improved dramatically. this made it easier for findings to be verified or disproved by experiment.
What is the force of gravity on a 500-N woman standing on Earth's surface?
500N
A 1000-kg car and a 2000-kg car are hoisted the same distance in a service station. Raising the more massive car requires
A 1000-kg car and a 2000-kg car are hoisted the same distance in a service station. Raising the more massive car requires
We see many cases daily of people misrepresenting things and who soon thereafter are excused and accepted by their contemporaries. How is this different in science?
A discredited scientist won't get a 2nd chance from his peers!
Which of the following has the largest momentum relative to Earth?
A pickup truck speeding along a highway
Vector
An arrow that represents the magnitude and direction of a quantity
What did Aristotle believe about the relative speeds of fall for heavy & light objects?
Aristotle believed that heavier objects would fall more quickly than light objects.
Did Aristotle believe that forces are necessary to keep objects moving, or did he believe that once moving, they'd keep moving on their own?
Aristotle believed that objects required additional force(s) in order to keep moving.
Regarding the question "when a plant grows, where does the material come from?" Aristotle hypothesized by logic that all material came from the soil. Do you consider his hypothesis to be correct, incorrect, or partially correct? What experiments do you propose to support your choice?
Aristotle is incorrect, because plants can't grow w/out sunlight, water, and air (carbon dioxide & nitrogen at least.) My experiment would be to attempt to grow a plant in nothing but soil (control) with variables such air & sunlight removed. then test the other variables as well. Aristotle guessed based upon logic, he didn't perform experiments to test his ideas!
What idea of Aristotle's did Galileo discredit with his inclined-plane experiment?
Aristotle's idea of motion (he said there were 2 types: natural and violent.)
Why do we say that velocity is a vector and speed is not?
Because vectors must have magnitude and direction; speed tells us the magnitude, but it does not give us the direction an object is moving.
An object is placed exactly halfway between the Earth and the Moon. The object will fall toward the
Earth
Which dominated Galileo's method of extending knowledge: philosophical discussion, or experiment?
Galileo's method of gaining knowledge was to use experiments to find truth, not logic, assumptions, or reason.
A 1-kg object weighs nearly 10 N on Earth. Would it weigh more or less on the Moon?
Less
When you are in the way of a fast-moving object and can't get escape, you will suffer a smaller force if the collision time is
Long
What two quantities are necessary for a vector quantity?
Magnitude and direction
Where is your weight greater: on earth or the moon? How about your mass?
My weight is greater on the Earth; my mass is the same regardless of location.
must people choose between science and religion?
NEVER. b/c science can be publicly scrutinized, but religion is personal; unless your religion forces you to choose, you can be knowledgeable about both.
Name the force that occurs in a rope when both ends are pulled in opposite directions
Tension
An object lifted 10 m gains a certain amount of potential energy. If it is lifted 20 m, its gain in potential energy is
Twice as much
The most energy per unit mass can be extracted from
Uranium
If an object's kinetic energy is zero, what is its momentum?
Zero
What is science?
___ is the product of human curiosity about how the world works. (a body of knowledge that describes order & cases in nature) (also, an ongoing human activity dedicated to gathering and organizing knowledge about the world.)
Law
a general hypothesis, or statement about the relationship of natural quantities that has been tested over & over, and has not been contradicted. (aka 'principle')
Which has a greater momentum: an automobile at rest or a moving skateboard?
a moving skateboard!
Fact
a phenomenon about which competent observers who have made a series of observations, are in agreement.
Inertia
a property of objects which causes them to resist changes in motion. (the greater an objects mass, the more of this property they have)
Force
a push or a pull
Vector quantity
a quantity whose description requires BOTH magnitude & direction
Friction
a resistive force that opposes the motion/attempted motion of an object past another it's in contact with (or through a fluid.)
if gravity between the sun & earth suddenly vanished, Earth would continue moving in:
a straight-line path
Theory
a synthesis of a large body of information that includes well-tested & verified hypotheses about certain aspects of the natural world
When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, the contact time is about 10 times more than for a stiff-legged landing and the average force your body experiences is reduced by
about 10 times
A motor scooter undergoes acceleration when it decreases speed. changes direction. gains speed. all of the above
all of the above
Which has zero acceleration? an object at rest an object in mechanical equilibrium an object moving at constant velocity all of the above
all of the above
Hypothesis
an educated guess; a reasonable explanation of an observation that's not accepted as factual until tested repeatedly and proved by experiments.
psychological comfort is a benefit of having solid answers to religious questions. What benefit accompanies a position of not knowing answers?
an open and exploring mind; (thinking for oneself)
Why is physics considered to be the basic science?
because the other sciences are all built on physics!
how are science and religion similar?
because they both are motivated by curiosity for the natural, and both have a great impact on society.
Distinguish between velocity & acceleration
both are vector quantities. velocity deals with speed & direction, the rate at which an object changes its position acceleration (m/s^2) is any change in velocity, how fast an object is changing speed
Impulse=
change in momentum
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 point of view different in science?
competent scientists must be experts at changing their minds!
When bullets are fired from an airplane in the forward direction of motion, the momentum of the airplane
decreases
A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is
doubled
The force that accelerates a rocket in outer space is exerted on the rocket by the
exhaust gasses
Which of these forms of energy is NOT renewable?
fossil fuel power
You use a straw for a pea shooter. The speed of the pea emerging from the straw when you blow through it will be greater if the straw is
full length
Throughout the ages, what has been the general reaction to new ideas about established "truths?"
generally new ideas are rejected (even forbidden, )at first, but later accepted/viewed as beneficial. ex: geology, evolution, etc.
A clerk can lift containers a vertical distance of 1 m, or roll them up a 2-m-long ramp to the same elevation. With the ramp, the applied force needed is
half as much
What is the importance to people of learning nature's rules?
helps us predict possibilities in nature before we even experience them, and helps us connect things.
Which of the following are scientific hypotheses? a) Chlorophyll makes grass green b) Earth rotates about its axis because living things need an alternation of light & darkness c) Tides are caused by the moon
hypotheses are: chlorophyll makes grass green & tides are caused by the moon, because they can both be tested/proved wrong. b) is not a hypothesis because we can't test it/prove it wrong.
Two objects move toward each other due to gravity. As the objects get closer and closer, the force between them
increases
During each second of free fall, the speed of an object:
increases by the same amount
An object that has twice as much mass as another object also has twice as much
inertia
Which name is given to the property by which objects resist changes in motion?
inertia
Asteroids have been moving through space for billions of years. A friend says that initial forces from long ago keep them moving. Do you agree?
initial forces may have put them in motion, but *the reason they keep moving* is bc of their inertia (resisting moving if an object's at rest, or resisting cessation of movement if an object's in motion.)
Does the speedometer on a vehicle show average speed or instantaneous speed?
instantaneous speed
If a charging rhinoceros has momentum, it must also have
kinetic energy
According to Newton, the greater the distance between gravitationally interacting objects, the
less the gravitational forces between them
What are the units of measurement for weight and for mass?
mass is measured with Kg (kilograms,) weight is measured with N (newtons)
When a cannon fires a cannonball at a given speed, the smaller recoil speed of the cannon is due to different
masses
What is meant by the term 'supernatural?'
means: above nature.' refers to religious and philosophical topics, that lie outside of the realm of science.
A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater
momentum
A moving object has
momentum, speed, energy, & velocity
According to Newton, the closer gravitationally interacting objects are to each other, the
more the gravitational forces between them
Suppose a gun were made of strong lightweight material with a pellet that is more massive than the gun. Then firing speed is greater for the
recoiling gun
how are the concerns of science and religion different?
science focuses on the physical universe; religion focuses on spiritual matters like faith & belief. Science is a matter open to public scrutiny, but religion is a deeply personal matter.
Briefly distinguish between science & technology
science is concerned with gathering & organizing knowledge. technology allows us to use that knowledge, and to build tools that scientists need to conduct experiments.
you have a ball at rest in the middle of a toy wagon; when the wagon is pulled forward, the ball rolls against the back of the wagon. A friend asks what force pushes the ball to the back of the wagon. interpret the observation in terms of inertia.
technically, bc of inertia, the ball remains in the same location, but since the wagon is pulled forward, the ball hits the back of the wagon. friction may cause the ball to roll some, but if it weren't a factor, the ball would remain in place while the surface of the wagon rolled underneath it.
Mass
the amount of matter in an object. also, the amount of inertia an object has (resistance to motion) remains the same in relation to Earth vs outer space
Volume
the amount of space that an object occupies
Speed
the distance traveled per time
Weight
the force due to gravity on an object (or how much the object presses against a supporting force.) Varies in relation to earth vs outer space.
Air resistance
the force of friction acting on an object due to its motion in air
Support force
the force that supports an object against gravity (aka normal force)
When you weigh yourself, how does the support force of the scale acting on you compare with the gravitational force between you & the earth?
the forces are equal (otherwise you wouldn't be in static equilibrium-at rest)
Acceleration
the rate at which velocity changes with time. (this change in velocity can be either in magnitude, direction, or both.) usually measured in m/s^2 a= [(final velocity)-(initial velocity)] / time
Newton N
the scientific unit of force
Velocity
the speed of an object, AND its direction (that its moving)
Net force
the sum of all forces that act upon an object
The ultimate source of energy from fossil fuels is the
the sun
Hang time
the time one's feet are off the ground while doing a vertical jump
Kilogram Kg
the unit of mass.
Equilibrium rule
the vector sum of forces acting on a non-accelerating object equals zero. (sum of all forces=0)
what are the roles of equations in this class?
these are guides to thinking that show the connections between concepts in nature.
You're driving down the highway and a lovebug spatters onto your windshield. Which undergoes the greater force of impact?
they're both the same
You're driving down the highway and a lovebug spatters onto your windshield. Which undergoes the greater impulse?
they're both the same
If you push an object twice as far while applying the same force, you do
twice as much work
When you push an object a certain distance while applying twice the force, you do
twice as much work
Distinguish between speed & velocity
velocity describes how fast & in what direction an object is moving. Speed only describes how fast an object is moving speed= distance/time velocity= (change in position)/time
Which depends on location: weight or mass?
weight (varies based on the presence of gravity)
Free Fall
when an object falls without air resistance (is only acted upon by the force of gravity, not air resistance)
What is the test for whether or not a hypothesis is scientific?
whether there is a test for proving the hypothesis wrong. (if there isn't one, then it's not a scientific hypothesis.)
