Lesson 16
Static electricity is an example of what type of force?
(contact or non-contact)
non-contact
What is a field? Choose all that apply.
A. an area that exerts a noncontact force
B. an area that exerts a contact force
C. a visible area
D. an area that surrounds an object
E. an area where energy is stored
A. an area that exerts a noncontact force
D. an area that surrounds an object
E. an area where energy is stored
What is motion?
movement
Scientists often study how parts work together as a whole. This is called a ______.
framework, hypothesis, system, variable
system
Which question would be asked by a scientist, and which would be asked by an engineer?
1. Can we create a blood pressure medicine with fewer side effects?
2. What causes high blood pressure?
1. engineer
2. scientist
What is static electricity?
a buildup of negatively charged particles on the surface of an object
What is current electricity?
A flow of negatively charged particles.
What is acceleration, and when can it occur?
A change in motion.
It occurs when an object speeds up, slows down, or changes direction.
Both speed an velocity involve a change in:
A. time
B. direction
C. position
D. both A and C
D. both A and C
A balloon is rubbed against a wool sweater. When the balloon is placed near some bits of paper, the paper jumps toward the balloon. This is an example of which type of electricity?
static, current
static
Iron filings moving toward a magnet is evidence that a field exists.
What type of field would cause this?
magnetic field
Which of these is evidence that a magnetic field exists?
A. A ball rolls downward until it reaches flat land.
B. A magnet moves toward another magnet.
C. When you push down on a spring, you feel it pushing back.
D. Both B and C.
B. A magnet moves toward another magnet.
30 km/hr
Which of the following are systems?
A. the living and nonliving parts of a pond.
B. a man walking a dog
C. a pencil sharpener
D. all of these are systems
D. all of these are systems
Scientists use models to study processes. Which of these processes cannot be viewed directly but can be studied with a model? (choose more than 1)
1. How forces spread air pollution
2. How viruses enter the body
3. A building under construction
4. Molecules of salt dissolving in water
1. How forces spread air pollution
2. How viruses enter the body
4. Molecules of salt dissolving in water
Which of these provides evidence that static electricity produces a field?
A. Hair stands on end when a child moves down a slide.
B. Bits of paper move towards a balloon.
C. Socks right out of the dryer bending toward each other.
D. All of the above.
D. All of the above.
If you bring a compass near a flowing electric current, you will see the needle move. Why?
A. A compass requires electricity to make it work.
B. The needle of a compass will spin when a contact force is exerted.
C. Any object that comes near a compass will make its needle move.
D. Electric current creates a magnetic field that exerts a force on the compass.
D. Electric current creates a magnetic field that exerts a force on the compass.
A toy car travels around a circular track at a constant speed. Which statements are true?
A. The car is accelerating.
B. The car's velocity is changing.
C. The car is not accelerating.
D. The car's speed is changing.
A. The car is accelerating.
B. The car's velocity is changing.
An American eagle flies 120 km in two hours. What is the average speed of the eagle?
60 km/hr
A passenger sitting on a bus holders a backpack. A person on the sidewalk observes the bus going by. Which statement is correct?
A. the backpack is not moving.
B. the backpack is moving.
C. the correct answer depends on the frame of reference.
C. the correct answer depends on the frame of reference.
From the passenger's frame of reference, the backpack is not moving.
From the observer's frame of reference, the backpack is moving.
Does static electricity produce a magnetic or an electric field?
electric field
Does current electricity produce a magnetic or an electric field?
magnetic field
What is the difference between velocity and speed?
speed is a measurement of how much an object's position changes over time. For example, a car's speed could be 50 mph (miles per hour).
velocity is the motion and direction of an object. For example, a car's velocity could be 50 mph, North.
Frame of reference can also be called point of view.
A passenger is sitting on a moving train. The train is traveling 70 km/hr. Using Earth as the frame of reference, what is the motion of the passenger?
no motion, 20 km/hr, 35 km/hr, 70 km/hr
70 km/hr
Identify the false statement, and tell why it is false.
1. A change in velocity occurs only when an object speeds up.
2. A change in direction is one type of acceleration.
3. Speed is a measure of how far an object moves in a certain amount of time.
1. A change in velocity occurs only when an object speeds up.
Velocity is determined by both direction and speed. An object's velocity can change if it changes speed or direction.