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Speed Velocity and Acceleration Everything You Need To Know About Motion.

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Presentation on theme: "Speed Velocity and Acceleration Everything You Need To Know About Motion."— Presentation transcript:

1 Speed Velocity and Acceleration Everything You Need To Know About Motion

2 Motion Motion is just a change in position. To describe how an object moves you need A ruler to measure where an object is. And a clock to measure when an object is.

3 Here is a little bug located at 0 cm at 0 seconds.

4 10 seconds later he is at 50 cm.

5 SPEED The speed of the bug is just his distance traveled divided by how long it takes. Speed = distance/time Speed = 50 cm/10 s = 5 cm/s

6 Speed is just how fast something is moving. Speed is always a positive number. Quantities that can be described by a single number are called scalars.

7 MORE SCALARS TEMPERATURE VOLUME MASS STUDENTS IN A ROOM ENERGY

8 VELOCITY Velocity is speed and direction. Velocity is how fast and which way. Quantities that have direction are called vectors.

9 MORE VECTORS ACCELERATION FORCE DISPLACEMENT MOMENTUM

10 Suppose our bug starts off at 100 cm.

11 And ends up at 80 cm 10 seconds later.

12 Calculating velocity is a little more complicated than calculating speed. Velocity = change in position/time Velocity = (final position – initial position)/time Velocity = (80cm – 100cm)/10 seconds Velocity = - 2 cm/s

13 For objects moving along a straight line A positive velocity means moving to the right. (usually) A negative means moving to the left. (usually)

14 A negative velocity does not mean an object is moving slower than zero cm/s. You can’t move slower than standing still. It just means an object is moving in a certain direction.

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16 ACCELERATION Acceleration is a change in velocity. So an object accelerates if it Speeds up Slows down Or changes the direction it is moving,

17 Acceleration = change in velocity/time Acceleration = (final velocity – initial velocity)/time Acceleration has units of velocity/time (meters per second)/seconds Or m/s/s or m/s 2

18 confusion Acceleration, like velocity, has direction. For objects moving along a straight line the direction of an object’s acceleration is denoted by plus or minus.

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20 Acceleration = (30 m/s – 0 m/s)/10 s a = 3 m/s/s The car’s velocity is increasing 3 m/s per second. The car is accelerating towards the right.

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22 a = (0m/s – 20 m/s)/10 s a = - 2 m/s/s Although the car is moving to the right It is accelerating to the left!

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24 a = (final velocity – initial velocity)/time a = ( -30 m/s – 0 m/s)/ 10 s a = - 3 m/s/s The car is both moving to the left and accelerating to the left. Negative acceleration does not always mean an object is slowing down!

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29 Newton’s Three Laws Newton showed that these laws of motion, combined with his law of universal gravitation, explained Kepler's laws of planetary motion.law of universal gravitationKepler's laws of planetary motion

30 1 = Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. law of inertia

31 2=The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector. law of resultant force

32 3= For every action there is an equal and opposite reaction. law of reciprocal actions


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