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The four kinematic equations which describe an object's motion are: There are a variety of symbols used in the above equations and each symbol has a specific.

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Presentation on theme: "The four kinematic equations which describe an object's motion are: There are a variety of symbols used in the above equations and each symbol has a specific."— Presentation transcript:

1 The four kinematic equations which describe an object's motion are: There are a variety of symbols used in the above equations and each symbol has a specific meaning. There are a variety of symbols used in the above equations and each symbol has a specific meaning. d – the displacement of the object. (we use x & will also use y) d – the displacement of the object. (we use x & will also use y) t – the time for which the object moved. t – the time for which the object moved. a – the acceleration of the object. a – the acceleration of the object. v i – the initial velocity of the object. v i – the initial velocity of the object. v f – the final velocity of the object. v f – the final velocity of the object.

2 The four kinematic equations which describe an object's motion are: If there is NO AIR RESISTANCE ALL objects, regardless of weight & size, will fall at the same acceleration. The Acceleration of gravity: g= m/s/s

3 Position Of Free Falling Object At Regular Time Intervals The position of the free- falling object at regular time intervals, every 1 second, is shown. The fact that the distance which the ball travels every interval of time is increasing is a sure sign that the ball is speeding up as it falls downward. The position of the free- falling object at regular time intervals, every 1 second, is shown. The fact that the distance which the ball travels every interval of time is increasing is a sure sign that the ball is speeding up as it falls downward.

4 Velocity Of Free Falling Object At Regular Time Intervals Assuming that the position of a free-falling ball dropped from a position of rest is shown every 1 second, the velocity of the ball will be shown to increase Assuming that the position of a free-falling ball dropped from a position of rest is shown every 1 second, the velocity of the ball will be shown to increase

5 Velocity Of Free Falling Object At Regular Time Intervals Observe that the line on the graph is curved. A curved line on a position vs. time graph signifies an accelerated motion. Since a free-falling object is undergoing an acceleration of g = 10 m/s/s (approximate value), you would expect that its position-time graph would be curved. A closer look at the position-time graph reveals that the object starts with a small velocity (slow) and finishes with a large velocity (fast). Since the slope of any position vs. time graph is the velocity of the object, the initial small slope indicates a small initial velocity and the final large slope indicates a large final velocity. Last, but not least, the negative slope of the line indicates a negative (i.e., downward) velocity. Observe that the line on the graph is curved. A curved line on a position vs. time graph signifies an accelerated motion. Since a free-falling object is undergoing an acceleration of g = 10 m/s/s (approximate value), you would expect that its position-time graph would be curved. A closer look at the position-time graph reveals that the object starts with a small velocity (slow) and finishes with a large velocity (fast). Since the slope of any position vs. time graph is the velocity of the object, the initial small slope indicates a small initial velocity and the final large slope indicates a large final velocity. Last, but not least, the negative slope of the line indicates a negative (i.e., downward) velocity.A curved line on a position vs. time graphA curved line on a position vs. time graph

6 Velocity Of Free Falling Object At Regular Time Intervals look at the velocity-time graph reveals that the object starts with a zero velocity (starts from rest) and finishes with a large, negative velocity; that is, the object is moving in the negative direction and speeding up. An object which is moving in the negative direction and speeding up is said to have a negative acceleration look at the velocity-time graph reveals that the object starts with a zero velocity (starts from rest) and finishes with a large, negative velocity; that is, the object is moving in the negative direction and speeding up. An object which is moving in the negative direction and speeding up is said to have a negative acceleration This analysis of the slope on the graph is consistent with the motion of a free-falling object – an object moving with a constant acceleration of 10 m/s/s in the downward direction. This analysis of the slope on the graph is consistent with the motion of a free-falling object – an object moving with a constant acceleration of 10 m/s/s in the downward direction.

7 How Fast? The velocity of a free-falling object which has been dropped from a position of rest is dependent upon the length of time for which it has fallen. The formula for determining the velocity of a falling object after a time of t seconds is: The velocity of a free-falling object which has been dropped from a position of rest is dependent upon the length of time for which it has fallen. The formula for determining the velocity of a falling object after a time of t seconds is: v f = v i + gt v f = v i + gt where g is the acceleration of gravity (approximately -10 m/s/s on Earth; its exact value is m/s/s). The equation above can be used to calculate the velocity of the object after a given amount of time. where g is the acceleration of gravity (approximately -10 m/s/s on Earth; its exact value is m/s/s). The equation above can be used to calculate the velocity of the object after a given amount of time.

8 How FAST ? Example t = 6 s t = 6 s v f = (0 m/s) + (10 m/s 2 ) (6 s) = 60 m/s v f = (0 m/s) + (10 m/s 2 ) (6 s) = 60 m/s t = 8 s t = 8 s v f = (0 m/s) + (10 m/s 2 )(8 s) = 80 m/s v f = (0 m/s) + (10 m/s 2 )(8 s) = 80 m/s

9 How Far? The distance which a free-falling object has fallen from a position of rest is also dependent upon the time of fall. The distance fallen after a time of t seconds is given by the formula below: The distance which a free-falling object has fallen from a position of rest is also dependent upon the time of fall. The distance fallen after a time of t seconds is given by the formula below: x = ( 1 / 2 ) g t 2 x = ( 1 / 2 ) g t 2 where g is the acceleration of gravity (approximately -10 m/s/s on Earth; its exact value is m/s/s). The equation above can be used to calculate the distance traveled by the object after a given amount of time. where g is the acceleration of gravity (approximately -10 m/s/s on Earth; its exact value is m/s/s). The equation above can be used to calculate the distance traveled by the object after a given amount of time.

10 How FAR ? Example t = 1 s t = 1 s x = ( 1 / 2 ) (-10 m/s 2 ) (1 s) 2 = -5 m x = ( 1 / 2 ) (-10 m/s 2 ) (1 s) 2 = -5 m t = 2 s t = 2 s x = ( 1 / 2 ) (-10 m/s 2 ) (2 s) 2 = -20 m x = ( 1 / 2 ) (-10 m/s 2 ) (2 s) 2 = -20 m t = 5 s t = 5 s x = ( 1 / 2 ) (-10 m/s 2 ) (5 s) 2 = -125 m x = ( 1 / 2 ) (-10 m/s 2 ) (5 s) 2 = -125 m The NEGATIVE displacement, indicates that the object is falling DOWN


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