Презентация Mechanics. Kinematics онлайн

Содержание слайда: Mechanics Kinematics

Содержание слайда: Kinematics is a way of describing the motion of objects without consideration of the reasons that cause this motion. Motion is a change in the position of a particle or a body in three-dimensional space. Translational motion occurs when the path traced out by any particle is exactly parallel to the path traced out by every other particle in the body. Material point (alternatively, a classical particle) is the body, whose size may be neglected in the given conditions. Rigid body is the body in which all the distances between the component particles are constant.

Содержание слайда: Reference frame In order to describe the motion the reference frame is necessary. It consists of: 1. A coordinate system 2. A time measurer 3. A set of physical reference points that uniquely fix (locate and orient) the coordinate system. The coordinate system is used to describe the position of a point in space. It consists of: An origin at a particular point in space A set of coordinate axes with scales and labels Choice of positive direction for each axis: unit vectors

Содержание слайда: 3 basic kinematic variables: 3 basic kinematic variables: the position of an object is simply its location in space the velocity of an object is how fast it is changing its position the acceleration of an object is how fast the velocity is changing

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Содержание слайда: Velocity Velocity is the rate of change of the particle’s position vector with respect to time. velocity is a vector quantity: “How fast and in which direction” direction of the velocity vector is tangent to the trajectory of the particle units: m/s, km/hr Average velocity

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Содержание слайда: Speed

Содержание слайда: Rectilinear uniform motion Rectilinear uniform motion: the object travels in a straight line and covers equal distances in equal intervals of time. Velocity is constant: Speed is , where the distance l is covered in time t Equation for coordinate of the object traveling along the OX axis:

Содержание слайда: Accelerated motion: non-uniform motion when velocity of the object varies with time. Rectilinear uniformly accelerated motion: the object travels in a straight line and its velocity increases or decreases by equal amounts in equal intervals of time. Acceleration rate of change of velocity with respect to time “How fast the velocity is changing” acceleration is a vector quantity units: m/s/s or m/s2 , m·s-2

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Содержание слайда: Projectile Motion Projectile motion is a form of motion in which a body or particle (called a projectile) is thrown near the Earth's surface, and it moves under the action of gravity only. g is the acceleration due to gravity ; g = 9.8 m/s2 If an object is in FREE FALL, gravity will change an objects velocity by 9.8 m/s every second. The acceleration due to gravity: ALWAYS ACTS DOWNWARD IS ALWAYS CONSTANT near the surface of Earth (air resistance is negligible)

Содержание слайда: Motion of the projectile thrown vertically

Содержание слайда: Motion of the projectile thrown horizontally

Содержание слайда: Motion of the projectile thrown horizontally

Содержание слайда: Motion of the projectile thrown at an angle above the horizontal

Содержание слайда: Motion of the projectile thrown at an angle above the horizontal Equations for coordinates:

Содержание слайда: Complementary values of the initial angle α result in the same value of the horizontal range.

Содержание слайда: Rotational motion Rotational motion occurs if every particle in the body moves in a circle about a single line. This line is called the axis of rotation.

Содержание слайда: Angular displacement Angular velocity, also known as angular frequency

Содержание слайда: Uniform circular motion is the case when the body moves at a constant speed in a circular path, but still has an acceleration. The velocity vector of the body is not constant: it has constant magnitude, but changing direction. Uniform circular motion is the case when the body moves at a constant speed in a circular path, but still has an acceleration. The velocity vector of the body is not constant: it has constant magnitude, but changing direction. The acceleration due to change in the direction is called centripetal. It is directed at all times towards the axis of rotation, and its magnitude is:

Содержание слайда: Example: quantitative determination of v and a from s or How to calculate v and a from s

Содержание слайда: Example:

Содержание слайда: Example: You are driving through town at 12 m/s when suddenly a ball rolls out in front of your car. You apply the brakes and begin decelerating at 3.5 m/s/s. How far do you travel before coming to a complete stop?

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