Forces and Motion
What is the equation for calculating speed?
speed = distance/time
What is gravity?
Gravity is a force that acts to pull objects together.
What is Inertia?
The tendency of an object in motion to stay in motion and an object at rest to stay at rest.
What is friction?
A force that resists the movement of one surface past another surface.
What is air resistance?
friction caused by gas molecules in the air hitting an object and slowing it down.
What does 15 km/hr mean?
It means the object travels 15 kilometers in 1 hour
What effect does gravity have on falling objects?
Gravity makes falling objects accelerate.
How do we overcome inertia?
Using a force
What types of surfaces produce the least amount of friction?
Smooth, slippery, icy, or waxed surfaces.
Name two examples of a streamlined object
Jet planes, bullet trains
What is the difference between speed and velocity?
Speed measures how far something travels and velocity is the rate it travels and direction of the objects movement.
What is the difference between mass and weight?
Mass is the amount of matter in an object. Weight is the force gravity exerts on an object.
You overcome its inertia by applying a force such as a push on the pedals.
What affect do oil and grease have on friction?
they make surfaces slip more easily (reducing the friction).
How does air resistance affect the way objects move?
Air resistance pulls on objects slowing them down.
Find the speed of a car traveling 150 kilometers in 2 hours
speed = distance/time
speed = 150 km/2 hours
speed = 75 km/hr
Your weight would increase because Jupiter is more massive and would have a stronger gravitational pull.
What does it mean to say that forces always work in pairs?
When a force pushes in one direction, another force always pushes with equal strength in the opposite direction.
Name two ways to increase friction
apply brakes to wheels, put sand or gravel on icy ground, make the surface more rough
How is flying a kite an example of air resistance?
The large surface area of the kite resists the wind causing the kite to rise upward as air blows against it.
True or False? When you change direction you change your speed and velocity.
False. When you change direction you do NOT necessarily affect your speed, but you DO change your direction.
Suppose you are on the moon and you jump in the air. What would happen in comparison to if you made the same jump on Earth?
You could jump higher and farther on the moon than on Earth and stay afloat longer on the moon than Earth because the force of gravity on the moon is mch less than the force of gravity on Earth.
How do forces work in pairs when a frog jumps off a water lily leaf? Identify the action and reaction force in this scenario.
If you have to walk on ice, what type of boots or shoes would you want to wear to prevent you from slipping?
You would want to wear a shoe or boot with rubbery soles, a rough pattern/texture, something that provides more friction to prevent you from slipping on the ice.
How can you reduce air resistance when riding a bike?
You can wear tight fitting clothes and streamlined helmets and keep your head down and arms and legs close to your body.