Section 1: Measuring Motion
vocabulary
1) Motion: an object's change in position relative to a reference point
2) Speed: the distance traveled divided by the time interval during which the motion occurred
3) Velocity: the speed of an object in a particular direction
4) Acceleration: the rate at which velocity changes over time; an object accelerates if its speed, direction, or both change
2) Speed: the distance traveled divided by the time interval during which the motion occurred
3) Velocity: the speed of an object in a particular direction
4) Acceleration: the rate at which velocity changes over time; an object accelerates if its speed, direction, or both change
section summary
This section discussed "Measuring motion". All motion (vocabulary word 1) is observed from a reference point (the point where an object's motion is observed) or a common reference point and is described with reference directions (Ex: North, South, East, West, Up or Down). Speed (vocabulary word 2) depends on distance and time and average speed can be calculated by dividing the total distance by the total time. The SI units for speed include meters per second (m/s), kilometers per hour (km/h), feet per second (ft/s), and miles per hour (mi/h). Next is Velocity. Velocity (vocabulary word 3) is the speed of an object in a particular direction (Ex: 15 m/s east). Velocity is only constant when speed and direction are also constant. For example, if a car is going 65 mi/h north and ten it goes 45 mi/h north, the velocity has changed. Velocities can also be combined. For example if a person is walking at a velocity of 2 mi/h south and the wind is blowing at a velocity of 3.5 mi/h south, then the persons velocity is 5.5 mi/h south. However, if the person is walking at a velocity of 2 mi/h north and the wind is blowing at a velocity of 3.5 mi/h south, the persons velocity becomes 1.5 mi/h north.Lastly, is acceleration. Acceleration (vocabulary word 4) is the rate at which velocity changes. An increase in velocity is positive acceleration and a decrease in velocity is negative acceleration or deceleration. You can calculate the acceleration of an object by subtracting the starting velocity from the final velocity and devidig the answer by the time it takes to change velocity.
section 2: What is force?
vocabulary
1) Force: a push or a pull exerted on an object in order to change the motion of the object; force has size and direction
2) Newton: the SI unit for force (symbol, N)
3) Net Force: the combination of all of the forces acting on an object
2) Newton: the SI unit for force (symbol, N)
3) Net Force: the combination of all of the forces acting on an object
section summary
This section discussed force, but what is force? Force (vocabulary word 1) is simply a push or pull on an object to change its motion, and is measured in newtons (vocabulary word 2), which is the SI unit for force. However, just because force is exerted on an object does not mean it will move (Ex: Trying to move heavy objects). There are also forces that can't be seen with the naked eye, unseen forces (Ex: gravity).
Net force (vocabulary word 3) is the combination of all of the forces acting on an object. For example, if a boy is pushing a piano at 20 N to the right and a girl is pulling the piano at 25 N to the right, the net force would be 45 N to the right. Another example would be if a pig is pulling a rope to the left at 10 N, and if a goat is pulling the rope to the right 12 N, the the net force would be 2 N to the right.
There are also balanced and unbalanced forces. When the forces on an object produce a net force of 0 N, the forces are unbalanced. Balanced forces do not cause an object to move and do not change the motion of a moving object. When the net force on an object is not 0 N, the forces on the object are unbalanced, and unlike balanced forces, unbalanced forces produce a change in motion such as a change in speed or direction. Unbalanced forces are necessary to cause a nonmoving object to start moving.
Net force (vocabulary word 3) is the combination of all of the forces acting on an object. For example, if a boy is pushing a piano at 20 N to the right and a girl is pulling the piano at 25 N to the right, the net force would be 45 N to the right. Another example would be if a pig is pulling a rope to the left at 10 N, and if a goat is pulling the rope to the right 12 N, the the net force would be 2 N to the right.
There are also balanced and unbalanced forces. When the forces on an object produce a net force of 0 N, the forces are unbalanced. Balanced forces do not cause an object to move and do not change the motion of a moving object. When the net force on an object is not 0 N, the forces on the object are unbalanced, and unlike balanced forces, unbalanced forces produce a change in motion such as a change in speed or direction. Unbalanced forces are necessary to cause a nonmoving object to start moving.
section 3: Friction: A force that opposes motion
vocabulary
1) Friction: a force that opposes motion between two surfaces that are in contact
section summary
This section discussed friction. Friction (vocabulary word 1) is a force that opposes motion between two surfaces that are in contact. The amount of friction depends on the force pushing the surfaces together. Weight also increases friction between objects. The roughness also effects friction. The rougher an object is, the more friction there will be.
There are also two types of friction. The first type of friction is kinetic friction, which is friction between moving surfaces. Kinetic friction can then be further split into sliding kinetic friction (Ex: sliding a chair on the ground to move it) and rolling kinetic friction (Ex: putting wheels on the chair and rolling it to move it). Sliding kinetic friction also usually requires more energy to perform then rolling kinetic friction. The second main type of friction is static friction which is when a force is applied to an object but does not cause the object to move.
Friction can also be both harmful and helpful. For example, friction can wear down car parts which can be harmful, but that same friction also causes parts of the car to work properly, which is helpful. Friction however can also be reduced and increased. Friction can be reduced by lubricants (which are substances that are applied to surfaces to reduce friction between surfaces) and smoothing the rough surfaces. For example, waxes and oils are used to smooth the rough surfaces in cars. Friction can be increased by making surfaces rougher and increasing the force pushing the surfaces together. For example, pushing down harder on a scrubber to clean a dirty pan.
There are also two types of friction. The first type of friction is kinetic friction, which is friction between moving surfaces. Kinetic friction can then be further split into sliding kinetic friction (Ex: sliding a chair on the ground to move it) and rolling kinetic friction (Ex: putting wheels on the chair and rolling it to move it). Sliding kinetic friction also usually requires more energy to perform then rolling kinetic friction. The second main type of friction is static friction which is when a force is applied to an object but does not cause the object to move.
Friction can also be both harmful and helpful. For example, friction can wear down car parts which can be harmful, but that same friction also causes parts of the car to work properly, which is helpful. Friction however can also be reduced and increased. Friction can be reduced by lubricants (which are substances that are applied to surfaces to reduce friction between surfaces) and smoothing the rough surfaces. For example, waxes and oils are used to smooth the rough surfaces in cars. Friction can be increased by making surfaces rougher and increasing the force pushing the surfaces together. For example, pushing down harder on a scrubber to clean a dirty pan.
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section 4: Gravity: A force of attraction
vocabulary
1) Gravity: a force of attraction between objects that is due to their masses
2) Weight: a measure of gravitational force exerted on an object; its value can change with the location of the object in the universe
3) Mass: a measure of the amount of matter in an object.
2) Weight: a measure of gravitational force exerted on an object; its value can change with the location of the object in the universe
3) Mass: a measure of the amount of matter in an object.
section summary
This section discussed gravity. Gravity (vocabulary word 1) is a force of attraction between objects that is due to their masses. Gravity is a result of mass (more mass = greater gravity). For example, in comparison to everything on Earth, Earth has a huge mass which means in also has a really intense gravitational force. So, due to the earths gravity the screen you're looking at stays in place instead of drifting off elsewhere.
Long ago people wondered why objects fell to the ground in the way they did. This question was then answered supposedly by one Sir Isaac Newton who observed a falling apple and concluded that unbalanced forces caused the apple to fall and are always required to cause any object to move. He then labeled this force gravity. Newton then summarized his theory that describes the relationships between gravitational force, mass, and distance as the law of universal gravitational. It it universal because it applies to all objects in the universe with mass. This law is composed of two parts. First (as stated earlier), as mass increases gravity also increases. For example, gravitational force between small objects is small, but gravitational force between larger objects is greater. The second part of the law of universal gravitation is that as distance increases, gravitational force decreases. For example, The further you are away from something, the weaker its gravitational force is on you.
Weight (vocabulary word 2) is also a measure of gravitational force. Weight is usually referred to as Earth's gravitational force on an object, but weight can also be a measure of the gravitational force exerted on objects by the moon or other planets. People also commonly get mass and weight mixed up, but it's quite simple really. As gravity changes, weight changes, but mass is always constant. Mass (vocabulary word 3) is just the amount of matter in an object. Gravitational force is approximately the same everywhere on Earth, so it may seem as if weight and mass are always the same, but if the gravitational force changed, then your weight would change, but your mass would stay the same.
Lastly, are measuring weight & mass. Weight is commonly measured in pounds (lb.), but it can also be measured in newtons (N). This is due to the fact that newtons are a measure of force, and gravity is a force, and weight is a measure of gravity. Next, is mass. Mass can be measured in kilograms (kg), grams (g), and milligrams (mg), but it is also measured in newtons. For example, 200 g weighs about 2 N.
Long ago people wondered why objects fell to the ground in the way they did. This question was then answered supposedly by one Sir Isaac Newton who observed a falling apple and concluded that unbalanced forces caused the apple to fall and are always required to cause any object to move. He then labeled this force gravity. Newton then summarized his theory that describes the relationships between gravitational force, mass, and distance as the law of universal gravitational. It it universal because it applies to all objects in the universe with mass. This law is composed of two parts. First (as stated earlier), as mass increases gravity also increases. For example, gravitational force between small objects is small, but gravitational force between larger objects is greater. The second part of the law of universal gravitation is that as distance increases, gravitational force decreases. For example, The further you are away from something, the weaker its gravitational force is on you.
Weight (vocabulary word 2) is also a measure of gravitational force. Weight is usually referred to as Earth's gravitational force on an object, but weight can also be a measure of the gravitational force exerted on objects by the moon or other planets. People also commonly get mass and weight mixed up, but it's quite simple really. As gravity changes, weight changes, but mass is always constant. Mass (vocabulary word 3) is just the amount of matter in an object. Gravitational force is approximately the same everywhere on Earth, so it may seem as if weight and mass are always the same, but if the gravitational force changed, then your weight would change, but your mass would stay the same.
Lastly, are measuring weight & mass. Weight is commonly measured in pounds (lb.), but it can also be measured in newtons (N). This is due to the fact that newtons are a measure of force, and gravity is a force, and weight is a measure of gravity. Next, is mass. Mass can be measured in kilograms (kg), grams (g), and milligrams (mg), but it is also measured in newtons. For example, 200 g weighs about 2 N.
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