Chapter 15 - Forces & Motion Flashcards
Position
the location of an object
Motion
the change of position of an object
speed
tells you how the position of an object changes during a certain amount of speed
velocity
When you tell both the speed and the direction of an object. To describe the direction part of velocity, you can use compass directions or words such as right, left, up and down
acceleration
Is any change in the speed or direction of an object’s motion. So acceleration is any change of velocity. Slowing down is acceleration, just as speeding up is as well.
force
push or pull
inertia
Is the property of matter that keeps it moving in a strsight line and keeps unmoving matter at rest. All matter has inertia. A truck has more inertia than a motorcycle. It needs a bigger engine, because more force is needed to get it moving quickly. The more mass an object has, the more inertia it has. The more inertia an object has , the harder it is to change its motion.
gravity
is the force that pulls things toward Earth. Example: if you toss a ball upward, gravity pulls it back down to the ground.
gravitation
is a force that acts between all masses and causes them to attract one another. It acts everywhere all the time.
weight
is a force measured in Newtons (N). One newton is about the weight of an apple.
friction
is a force that resists the motion of objects, relative to each other, when the objects are touching. Friction slows down motion and stops it. The force of friction is always present when one surface touches another. Example: when you are on your bicycle and you apply the brakes, the rubber pads of your brakes create friction because they press against your wheel. The friction slows the wheel and you finally stop. Friction is measured in Newtons, just like other forces.
identify examples of friction
Rubbing both hands together to create heat. A sled sliding across snow or ice. Skis sliding against snow. A person sliding down a slide.
identify examples of inertia
your body movement to the side, when a car makes a sharp turn. Tightening of seat belts in a car when it stops quickly. A ball rolling down a hill will continue to roll unless friction or another force stops it.
identify examples of acceleration
a car that is speeding up or breaking
why is the force of gravity important?
Gravity is very important to our everyday lives. Without Earth’s gravity we would fly right off it. We’d all have to be strapped down. If you kicked a ball, it would fly off forever.
