Motion Lecture

Come on baby, do the

MOTION!

loco

A lecture by The PhysicsWhiz

Anything common to the previous pictures?

MOTION!

Motion defined 

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Any change in position with respect to a frame of reference. Frame of reference – any physical entity which could serve as basis in telling that an object is moving.

Mechanics the branch of Physics that is concerned with the analysis of the action of forces on matter or material systems. 

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Dynamics is the branch of mechanics that is concerned with the effects of forces on the motion of a body or system of bodies, especially of forces that do not originate within the system itself.

Kinematics branch of mechanics that studies the motion of a body or a system of bodies without consideration given to its mass or the forces acting on it

Unlocking of Difficulties Distance  Displacement  Speed  Velocity  Acceleration  Deceleration  Instantaneous Speed  Instantaneous Velocity 

Distance vs. Displacement 

Distance is the extent of space between two objects or places; an intervening space. It is also the total length traversed by a moving object. It is a scalar quantity.

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Displacement is the shortest length between two points. It is a vector quantity.

Consider this example. I traveled to meet her. I headed 2.0 m North, then 2.0 m East.  What distance did I travel? What was my displacement?  His distance is 4.0 m.  His displacement is 2.8 m, 45 deg N of E. 

Consider another example. Stacy ran swiftly to meet Christian. She headed 15m North, then 12m 25˚N of E, then finally 21m East until she gave the boy a hug!  What was her distance and displacement?  Distance = 48m, Displacement = 38m, 32˚N of E 

Speed vs. Average 

Speed is the ratio of distance traveled to time interval. It is a scalar quantity.

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Velocity is the ratio of change in position to time interval over which change takes place. It is a vector quantity.

the two terms can just be interchanged in an ordinary conversation, but they should have a distinction in Physics.

What do you call the device in your car that measures speed?

SPEEDOMETER

Consider this example. A sprinter runs for 15 seconds towards southeast and covers 6.0 x 10 m.  What is his speed? What is his velocity?  Speed is 4.0 m/sec.  Velocity is 4.0 m/sec, southeast. 

Acceleration vs. Deceleration Acceleration, in general, means change in velocity per unit time. Since it involves velocity which is a vector quantity, therefore, acceleration is likewise a vector quantity. 

Acceleration means it is increasing in speed.

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Deceleration means it is decreasing in speed.

Uniform vs. Non-uniform motion 

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An object in a uniform motion is moving in a straight line at constant speed. Rare type of motion.

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An object, on the other hand, that is moving in a speed that varies from time to time is said to be in a nonuniform motion. Such type of motion is the most common.

Accelerated Motion vs Uniformly Accelerated Motion 

Accelerated motion is achieved when a moving object is moving at a non-uniform fashion.

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Uniformly accelerated motion is attained when a moving object travels in straight line and the speed varies uniformly with time.

Describe the pictures.

I have a great day with you! Thank you so much.