Forces Basics
This force pulls objects toward the Earth.
Gravity
Q: Which surface has more friction: sandpaper or ice?
sandpaper
Why does a parachute slow a person falling?
It increases air resistance
Draw a ball falling from your hand. Show the force acting on it.
One arrow pointing down (gravity)
I pull you down and keep your feet on the ground.
I work all the time, but I can’t be seen.
What am I?
Gravity
In which direction does gravity pull objects on Earth?
down
Q: What is produced when you rub your hands together quickly?
: Which has more air resistance: a flat sheet of paper or a crumpled one?
flat sheet of paper
Draw a box being pushed across the floor. Show the forces acting on it.
I slow you down when you slide or stop.
Without me, you might slip and drop.
I happen when surfaces meet.
What force am I?
Friction
How does gravity change when an object has more mass?
Gravity becomes stronger
Q: Name one way to reduce friction between two surfaces.
add a liquid
Why does a feather fall slower than a rock?
it experiences more air resistance
Draw a feather falling through the air. Show the forces.
I only work when something moves through a gas.
The faster you go, the stronger I become.
I can be small for a rock but large for a parachute.
What force am I?
AR
In a vaccuum - what drops faster a feather or a bowling ball?
The same.
Why do car tires have rough treads instead of being smooth?
To increase friction
What would happen if there was no air resistance?
Objects would fall much faster because nothing would slow them down.
Draw a parachute falling. Show which force is stronger. (Draw a bigger arrow for the force that is stronger)
I can pull some metals close, but not all that you see.
I have two ends that work together, called poles—just like me.
Opposites attract, but likes push away.
You can’t see my force, but I work every day.
What am I?
Magnets
Q: How would your weight change on the Moon compared to Earth?
You would weigh less on the Moon
A parachutist jumps out of a plane. At first they fall quickly, then they slow down after opening the parachute. Explain what forces are acting and why the speed changes.
Gravity pulls the parachutist down. Air resistance pushes upward. When the parachute opens, air resistance increases, so they fall more slowly
What type of shape reduces air resistance?
streamlined
Draw a car moving along a road and show all the forces acting on it. Use arrows and label each force.
I help things float and keep them up high,
Even heavy ships don’t sink when I’m nearby.
I push upward in water, though I can’t be seen,
Without me, boats would dive straight down, not stay in between.
What am I?
Buoyancy