Physics: Kinematics

Physics: KinematicsAndy OnoratoGrade:12

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Kinematics equation 1 Kinematics equation 2 Kinematics equation 3

Force of Gravity Normal ForceForce Equation

Tension Force Frictional Force

Kinematics Equation 1

The first kinematics equation is v = v0 + at.This equations states that the speed of an object can be determined by first multiplying the acceleration by how long the object is traveling and then adding that speed to the initial speed of the object.

Example: A car that starts at rest accelerates uniformly for 5 sec at 3m/s2, how fast is the car going after that 5 sec?

v = v0 + atv = 0 + (3)(5)v = 15m/s

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Kinematics Equation 2

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The second kinematics equation is v2 = v02 + 2ax.

This equations states that the speed squared of an object can be determined by first multiplying the acceleration and the distance traveled of an object by 2, and then adding that speed to the initial speed squared of the object.Example: A boy is standing on the top of the bleachers with a super ball. He throws the ball straight at the ground at an initial speed of 5m/s. The bleachers are 30m tall and the acceleration due to gravity is 10m/s2. At what speed does the ball strike the ground?

v2 = v02 + 2ax

v2 = (5)2 + 2(10)(30)v2 = 625m/s v = 25m/s

Kinematics Equation 3

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The third kinematics equation is x = v0t + ½at2.This equations states that the distance an object travels can be determined by first multiplying the initial speed by how long the object travels at that speed. Then add that amount to ½ the acceleration multiplied by the time squared.Example: A girl is jogging at a constant speed of 2m/s. For 6 sec she accelerates at a rate of 1 m/s2. How far does she travel during her time of acceleration.

x = v0t + ½at2

x = (2)(6) + ½(1)(6)2

x = 12 + 18x = 30m

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Force EquationThe equation we can use to find the force is Force equals the mass multiplied by the acceleration. So if a 400g object is accelerating at a constant of 5m/s2, how much force does the object have?

F = ma

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Force of GravityThe force of gravity is the amount of force the object feels from gravity. It can be found by multiplying the mass times the acceleration due to gravity (9.8m/s2)Fg = mg

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Normal Forcethe normal force (FN) is the component, that keeps an object from pushing through another surface. For example, the surface of a floor or wall, preventing the object from penetrating the surface.

Tension Force

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The tension is the pulling force exerted by a string, cable, chain, etc on another object.

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Frictional ForceFriction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.

How fast does a ball hit the ground when dropped from a 20m building?

392 m/s2

19.8 m/s

10 m/s2

50 m/s2

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Physics Problem

Note that the tension force on each of the blocks is of the same magnitude. If the large block (5g) feels a force of 10 N, and the small block weighs 3 g, What force is exerted on the smaller block?

Answer

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Large Block F = ma10 = (5)a a = 2 m/s2

Small Block F = ma F = (3)(2) F = 6 N

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