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# Force and Motion Science Project

By Yujean Shin
by on 21 January 2015

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#### Transcript of Force and Motion Science Project

Force and Motion Scrapbook
By: Yujean Shin
Force
A force is a push or a pull. It can change an object's direction and speed.
One example of a force is Gravity.
A force is an action that changes or causes the motion of an object. It is a push or a pull. Forces can change an object's speed or direction.
Opening a door is a force. You make the door move.
Kicking a ball while it is moving is a force. That changes the speed of the ball. It goes faster.
If the ball was kicked and it changed direction, it is a force. Forces can change an object's direction.
The ball changes direction
from this to this.
Gravity
Gravity is the force that attracts objects towards the center of the earth or any other physical body with mass.
Friction
Friction is a force that resists motion between two surfaces that are touching each other. Friction is much greater on rough surfaces than smooth surfaces. It works in the opposite direction of motion. For example, when you push a chair, the floor creates a frictional force in the opposite direction (toward you) to resist the forward movement of the chair.
Inertia
Lever
Pulley
Wheel & Axle
Inclined Plane
Wedge
Screw
A lever is a simple machine. It allows a small force applied at one end to lift a heavy weight at the other. It is made of a bar or plank that pivots on a fulcrum. Force is applied at one point along the bar. That force is called effort force. The object the lever is lifting is called a load. What a lever will do depend on where the effort, load, and fulcrum are placed on the bar.
A pulley is a simple machine. It is made of a rope that goes over a grooved wheel. The wheel is grooved so that the rope stays on the wheel. A pulley lets you lift heavy objects more easily.
A wheel and axle is one of six simple machines. It is made of a wheel attached to an axle. An axle is a rod, and it goes through the center of the wheel. The wheel and axle rotate together. It is used to move objects.
An inclined plane is a simple machine. It is a slanted surface that makes it easier to lift an object. The longer the inclined plane, the easier it is. If the inclined plane is short and steep, it is hard to move from one level to another. However, when the inclined plane is long, you have to walk more.
A wedge is a simple machine. It is made of two inclined planes back to back. A wedge is used to cut or split objects apart.
A screw is a simple machine. It is an inclined plane wrapped around a cylinder. A screw is used to hold objects together.
The apples fall towards the center of the Earth.
Weight is how much gravity is pulling down on a object. On planets(or other physical body)that have a greater mass than Earth, you weigh more because more gravity pulls down on you.
Earth has six times as much mass than the moon, so you weigh six times as less on the moon than on Earth.
In the picture below, the ball would roll down the hill. Gravity makes it roll down.
Friction helps cars and bicycles stop. The friction between the brakes and the wheels of the car or bicycle helps it slow down.
In this picture, there is a bicycle brake on the top of the wheel. When the brake was pushed, the brake would push against the wheel and slow it down.
An ice rink is smooth, so there is less friction than a rough surface. It is easier to move across the ice with ice skates than rubber boots. The friction between the ice skates and the ice is less than the friction between the rubber boots and the ice.
When you rub your hands together, the friction between your hands generates heat. It makes your hands warm up.
The first of Issac Newton's laws of motion is also called the law of inertia. It states that if an object is still, it will stay still until a force acts on it. It also states that if an object is moving, it will keep on moving until a force acts on it. Things want to do what they are already doing. More massive objects have greater inertia than less massive objects. For example, it is much harder to push a train than a bicycle.
This is where the ball would travel.
Like on the left, the ball would stay still if it was still at first. If the ball was kicked, like on the right, the ball would keep going on forever
if
there wasn't a force acting on it. In your everyday life, forces would stop the ball. For example, if you kick a ball, it stops because of friction.
The train has more inertia than the pencil. The train is very hard to move, but a pencil is not hard to move.
A pencil doesn't take a lot of force to move.
A freight train takes a lot of force to move.
The ball is still.
The ball is moving in the direction the arrow is pointing.
When a car is moving, everything in the car is moving at the same speed as the car. If the car suddenly stopped, the things in the car would keep on going forward until a force (like your seat belt) stopped you.
Effort
This is a first-class lever. A first-class lever has the fulcrum in the middle. The load and effort are on either ends. The farther the fulcrum is to the load, the easier it is to lift the load.
An example of a first-class lever is a seesaw. One person pushes down(the effort) so the other person(the load) goes up, and the other person does the same thing(pushes down and makes an effort).
This is a second-class lever. It has the fulcrum on one end. The load is in the middle, and the effort is on the other end.
A wheelbarrow is an example of a second-class lever. The wheel is the fulcrum, the part in the middle is the load, and the handles you lift are the effort. When the handles are lifted, the load moves up.
This is a third-class lever. It is like the second-class lever, but the effort is in the middle and the load is on the other end.
fulcrum
effort
An example of a third-class lever is a tweezer. The load is what the tweezer lifts. The effort is in the middle of the fulcrum and the load. The fulcrum is where the two parts meet.
The blind cord on a window is an example of a pulley. There is a wheel at the top of the blinds. When you pull the cord, the blinds go up.
A movable pulley's wheel doesn't stay still. It is attached to the object the pulley is lifting. You pull up on the rope, and the object moves up.
If you combine a movable pulley and a fixed pulley, it makes work easier.
A crane has a fixed pulley and a movable pulley. The fixed pulley is at the top, and the movable pulley is at the bottom.
This is the movable pulley
This is the fixed pulley
It takes more effort to lift something with a fixed pulley than with a movable pulley. It takes more effort to lift something with a movable pulley than with both the fixed and movable pulleys. However, you have to pull a longer distance. The same work is done, but over a longer distance.
An example of a pulley is the chain and gear on a bike. The gear is the wheel, and the chain is the rope.
The wheels on the wagon are an example of a wheel and axle. When the wheel turns, the axle turns with it.
This is the wheel.
This is the axle.
A screwdriver is an example of a wheel and axle. The handle is the wheel, and the long part is the axle. You turn the wheel(handle) to get the screw into the wood.
A doorknob is an example of a wheel and axle. The axle is the part that goes through the door, and the wheel is the part you turn.
A slide is an example of an inclined plane. The part that you slide on is the inclined plane.
A ramp is an inclined plane. In the picture above, the box is being pushed up the inclined plane(ramp). It would be easier to get the box in the truck if the ramp was less steep. However, you would have to push the box farther because the board would be long.
The fan blades are inclined planes. As the fan blades spin around, they push air along their slanted surfaces.
A knife's blade is a wedge. It cuts through the cake.
An ax is a wedge. It is made of two inclined planes, and it splits wood.
The front of a ship is a wedge. It is made of two inclined planes, and it slices through water.
A regular screw is used to hold things together. It keeps things together better than a nail, but it takes more time to get it in wood.
The bottom of a lightbulb is a screw. The screw helps it stay in place.
The top of a bottle is a screw. The bottle cap and the top of the bottle has a screw in it so you can screw the top on.
(If the apples were in space, they'd probably float off. This is just saying that everything on Earth is being pulled towards the center of the Earth.)
This is a fixed pulley.
The wheel is fixed in one position.
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