Types of Forces
Name one contact force and one non-contact force
Example: friction (contact), gravity (non-contact).
What is the name of the force that opposes motion?
Friction
Brooke rubs a balloon on hair and hair sticks. Which force is responsible?
Electrostatic
According to Kepler’s observations, do planets closer to the Sun orbit faster or slower than planets farther away?
Closer planets orbit faster.
What tool would scientists across biology, physics, and engineering commonly use to measure forces?
Force Meter
Which type of force acts when two objects are touching and resisting motion between them?
Friction
Two students investigate how friction affects the speed of a toy car. They release the car from the same starting position on each surface and measure how long it takes for the car to stop.
What is the dependent variable?
The time it takes for the car to stop
When a magnet is moved farther from paperclips and fewer clips stick, what does that show about magnetic force and distance?
Magnetic force is stronger when closer; force decreases with distance.
What invisible force did Newton propose that explains why planets orbit the Sun and objects fall to Earth?
Gravity
Which claim best explains why scientists accept Newton’s gravity idea: repeated matching predictions or a single strong observation?
Repeated matching predictions and observations — replication and predictive success strengthen a scientific idea.
How is normal force related to gravity for an object resting on a flat surface? (Brief explanation)
It equals gravity for the object
If a car stops faster on sandpaper than on tile, what does that say about the friction on sandpaper relative to tile?
Sandpaper has greater friction than tile.
Given two charged pith balls showing attraction, what must be the signs of their charges?
Opposite charges (one positive, one negative) — e.g., A positive and B negative.
Which planet listed has the longest orbital period and why?
Mercury 0.24 Earth years
Earth 1.00 Earth years
Jupiter 11.86 Earth years
Saturn 29.46 Earth years
Saturn
Jupiter has a greater gravitational pull than Mars. How would the mass and weight differ if the same object was on Mars?
The mass of the object will be the same, but the weight will be different on each planet.
Identify whether gravitational, electric, and magnetic forces are contact or non-contact, and give one real-world example of each.
Various
A student measures average frictional force on tile as 7.5 N and another gets 8.5 N. Why does replication strengthen confidence in the result?
Because similar averages from independent replications reduce the chance the result arose from random error
Explain how electric force can be both attractive and repulsive.
Like charges repel, opposite charges attract
What is the difference between the geocentric model and the heliocentric model?
Geo- Earth centered
Helio- Sun Centered
"What made Newton's idea revolutionary was that this observable pattern applied everywhere. The same force that keeps our Moon orbiting Earth also keeps Jupiter's moons orbiting Jupiter and holds galaxies together."
Is Newton's explanation of gravity is considered a scientific theory or law?
Law because it describes an observable pattern in nature.
What is the similarity between friction and a normal force?
Both are contact forces
Padma is riding a bike down a hill. As she gets to the bottom, she applies the brakes to stop the bike’s forward movement. How is friction acting on the bike?
The brake pad rubbing on the front tire applies friction to stop
When is your test?
Wednesday 9/9
Given two planets with equal mass but one is twice as far from the Sun as the other, describe qualitatively how their orbital speeds compare and why?
The planet farther from the Sun moves more slowly because gravitational pull decreases with distance
A student measures an object on Earth and finds it has a mass of 5 kilograms and a weight of 49 newtons. If the same object were placed on a planet with twice the gravitational pull as Earth,what would happen to its mass and weight?
The object's mass would stay 5 kilograms, and its weight would be about 98 newtons.