midterm 1 Flashcards
Which of the following statements best represents Newton’s first law of motion?
Every object at rest, or in uniform motion, will remain in that state of motion unless compelled to do otherwise by forces acting upon it.
If an object is in uniform motion then the object will have a constant speed and direction.
True
Which of the following statements is true?
The mass of an object is always the same, but the weight of an object changes based on the acceleration of gravity acting on the object.
What are the units for distance, speed, and acceleration, respectively?
m, m/s, m/s2
If there were no air friction (a vacuum), and if a feather and a wrench were dropped from the same height at the same time they would hit the ground at different times.
False
What is the acceleration due to gravity of all objects on Earth?
9.8 m/s2,
32 feet/sec2,
22 miles/hour every second
If there was a green and red ball located at the same height. If the red ball was shot horizontally and the green ball was dropped which ball would hit the ground first?
Both balls would hit the ground at the same time
If a ball was thrown in the air, what is the acceleration of the ball the moment it reaches its maximum height and zero speed?
9.8 m/s2
What law of motion describes why it is easier to accelerate objects with little mass?
Newton’s 2nd law of motion
If someone was in outer space with no other objects nearby, and they threw a ball. What would happen to the ball?
The ball would go at the same speed and direction forever.
What would happen if you had two charges and you brought them close together?
The charges would attract one another if they were opposite charges and repel one another if they were the same charges.
All electric currents create magnetic fields.
true
Which of the following scientists came up with the idea for positive and negative charges?
Benjamin Franklin
What experiment was used to determine the charge of an electron?
Oil drop experiment
What type of electricity is used in our homes, and what type of electricity is used to charge our batteries? (Hint look up how cellphone chargers work)
Alternating current is used in our homes and direct current is used to charge our batteries.
A generator is a set of magnets turning inside coiled wires. As a turbine moves the generator the magnetic field changes within the coils causing an electric current or voltage.
true
A speaker is one example of an electromagnet.
true
If you were standing on a scale in a stopped elevator, what would happen to the your weight reading on the scale if the elevator started moving up?
Weight more than at rest
When a falling object experiences terminal velocity it stops accelerating, and moves at a constant speed.
true
What effects air friction for any object?
Surface Area
Speed
What are Newton’s three laws of motion? Can you identify them and apply them in everyday situations?
- Every object at rest, or in uniform motion will remain in that state of motion unless compelled to do otherwise by forces acting upon it. Qualitative.
- force = mass x acceleration. Quantitative. If you double the force on an object without changing its mass, the acceleration doubles.
- forces occur when two things interact with each other. The two resulting forces have the same strength and act exactly in opposite directions.
What is the acceleration due to gravity on Earth?
9.8 m/s^2
What is the acceleration due to an object thrown in the air?
same as gravity on earth just minus initial speed
What is mass? How are mass and weight related?
Mass-the characteristic of a body which determines how much it accelerates when a force is applied.
Weight- a measure of the force of gravity on a particular mass
What will hit the ground faster a heavy or a light object in a vacuum?
same time
If an object is given a horizontal force will it hit the ground sooner than another object dropped straight down at the same time? (Dropping a bullet vs. shooting a bullet)
same time
How does riding in an elevator affect your weight? When will you weigh more, less or the same?
weigh less down, weigh more up
If I tell you the acceleration of an object starting at rest could you tell me the velocity after a specific amount of time?
a change in an objects velocity is acceleratoin.
If I tell you the constant speed of an object could you tell me how far it traveled in a specific amount of time?
yes
If two pieces of tape are brought near one another and they are attracted or they are repelled what would cause the attraction or repulsion?
electrification, electro-magnetic. positively and negatively charged ions. ELECTRIC FORCE LAW. similar charges repel and dissimilar attract.
Why did the pie tins fly off the Van de Graaff generator?
because they had positive charges to repel them
What is the electrical model of matter? When there is an electric current, what always moves and what always stays in the same location?
Electrical model of matter is what it is made of. lightning pic. protons positive and electrons negative. electrons move while protons stick.
What would happen if I had two magnets and I brought them close together?
stick or repel
How is electricity generated all over the world?
because it is a giant magnet. electromechanical generators. electromagnetic induction.
How did J.J. Thomson discover the electron?
tube, metal plates in sealed ends, evacuated tube, injected small gas into it. connected battery, beam appeared.
How did Millikan discover the charge of the electron?
oil drop experiments. through a charged plate.
How can a magnet lose their magnetism?
heat and feromagnetic
How can you generate magnetism using electricity?
current flows through coil. iron bar with electrical current
If I have two objects with a force of F, mass M and m, separated by a distance d. What would happen to the force F if I separated the distance by 5d? ( Solve for the new force in terms of the original force. )
k
What is terminal velocity and what causes it?
constant velocity it can go and gravity. so when opposing force equals gravity force. no acceleration
What will happen if you change a magnetic field?
it’ll switch fields
What is a transformer used for? What type of electricity does it work on and what type does it not work on?
magnetic flux fluctuation going through wire current. DC dont work and AC work.
If I show you a plot, can you distinguish alternating current from direct current?
direct current is a steady flow of electrons in one direction, typically though a wire. AC is a current of electrons that changes direction of flow.
In your house where would you find alternating current, direct current, and static electricity respectively?
Ac used in home, battery charges is dc, and static, carpet is static
What type of electricity is more efficient AC or DC?
AC
What is the most common source of direct current?
batteries
