24. A free falling object is an object
that is falling under the sole
influence of gravity. Any object that
is being acted upon only by the force
of gravity is said to be in a state
of free fall.
Free-falling objects do not
encounter air resistance.
All free-falling objects (on
Earth) accelerate downwards at a
rate of 9.8 m/s/s
25. A free-falling object has an acceleration of
9.8 m/s/s, downward (on Earth). This
numerical value for the acceleration of a
free-falling object is such an important
value that it is given a special name. It is
known as the acceleration of gravity - the
acceleration for any object moving under the
sole influence of gravity. A matter of fact,
this quantity known as the acceleration of
gravity is such an important quantity that
physicists have a special symbol to denote it
- the symbol g.
Editor's Notes
Good afternoon ma’am, good afternoon classmates!
This is Jimmy Rivera, Gemina. Today we will be discussing about Motion, specifically, Motion graphs, the positive and negative displacement, constant acceleration, and the free falling.
Aside from diagram, the motion of an object can be represented using graphs. In physics these are called motion graphs. We can interpret the motion of an object by looking and interpreting the motion graph.
A graph is a visual representation that uses lines to show how two or more sets of measurements are related to each other.
There are three types of motion graphs these are, Position time graph, Velocity time Graph , and acceleration time graph.
The graph on which the instantaneous position x of a particle is plotted on the y-axis and the time t on the x-axis.
Now let us try graphing the data.
At 0s, the postion of the car is at 0m
After 5s, the position of the car is at 5m.
At 10s, the car is at 10m.
And finally at 15s, the car is at 15m.
Now let us draw a line to connet the dots.
We have now the graphical representation on the motion of the car. The graph we have just done is an example of Position-Time Graph.
So, we can use this graph to describe the position of an object at any time.
Example: what is the location of the car after 10s? The answer is 10m?
When the graph is plotted in terms of distance travelled by an object, and the time it took to covered such distance the graph is about distance time graph.
When the graph is plotted in terms of displacement and time. It is called Displacement Time Graph.
The diagonal line that connects the position is called the SLOPE. The slope in a graph gives an idea about the motion of an object.
The slope of the position time graph gives us the velocity of an object. Let us interpret the motion graph.
We can say that an object is moving at a contant velocity when an object is moving in equal distances in equal time interval without change its direction. It also indicates that the acceleration is zero.
Ex: a car in motion at a constant velocity like 1m/s
The slope of the graph indicates zero velocity. It means that the position of an object is at rest and its not moving.
our next graph is forming a curve line. The curve indicates that the motion or velocity of an object is changing.
So, the graphs shows nonconstant velocity or changing velocity. An object has an accelerated motion.
If the quantity involve in the graph is velocity and time, This is called velocity time graph.
The slope of the graph pertains acceleration of the object.
Let us now interpret the velocity time graph.
This velocity time graph indicates that the acceleration of an object is constant and the velocity of the object is changing at constant rate.
Horizontal slope in velocity time graph shows that the object has zero acceleration. This means that the body or object is moving in constant or uniform velocity.
For this graph, the slope is curving. This indicates that the acceleration of the object is not constant and it is increasing.
As you notice the slope of the graph is opposite to the direction of the velocity. This graphs shows that the object is decelerating. Deceleration always reduces speed. Negative acceleration, however, is acceleration in the negative direction in the chosen coordinate system.
Displacement is the change in position between an initial position and final position.
Displacement is a vector quantity and so has a direction.
Displacement is positive when an object moves in the positive direction. The final position will be further in the positive position than the initial position.
The acceleration of a particle is said to be constant if equal changes of velocity take place in equal intervals of time.
A stone dropped from a tower is a freely falling body moving under constant acceleration i.e, acceleration due to gravity (9.8 metres per second per second). A freely falling object is under the influence of the force of gravity alone (neglecting air resistance), and hence the motion of the object will be due to the acceleration due to gravity.
Tennis ball thrown vertically upwards
A tennis ball thrown vertically upwards experiences a constant deceleration due to gravity. Deceleration is the negative of acceleration. This implies that the velocity of the ball decreases with time. The value of the constant deceleration due to gravity is 9.8 metres per second per second. This implies that the velocity of the ball when it is thrown upwards decreases at the rate of 9.8 metres per second per second.
Ball rolling on an inclined plane
Neglecting friction between the ball and the inclined plane, the rolling ball experiences a component of the acceleration due to gravity (g sin x; where x is the angle of inclination of the plane). Hence the motion of the ball along the inclined plane is under the influence of constant acceleration.
Merry-go-round
The horses on the merry-go-round rotate with constant acceleration known as centripetal acceleration. Centripetal acceleration is typically experienced by objects moving in a circular path with constant speed but varying velocity. Such a motion is known as a uniform circular motion. The centripetal force is centre seeking and hence acceleration due to this force drives the objects (here, horse) towards the centre.
Motion of Moon around the Earth
The revolution of the Moon around the Earth can be explained as uniform circular motion. Moon is under the influence of the force of gravity of the Earth and experiences a constant centripetal acceleration.
Freefall refers to a situation in physics where the only force acting on an object is gravity and hence acceleration due to gravity. Freefall as its term says is a body falling freely because of the gravitational pull of the earth. This motion will have the effect of acceleration due to gravity. This type of motion will follow the three equations of motion under gravity.
Projectile motion is another important category of free-fall problems. Although these events unfold in the three-dimensional world, for basic physics purposes, they are considered as two-dimensional on paper.
A very unique but interesting property of the acceleration due to gravity is that it is the same for all masses. This was far from the self-evident fact, until the days of Galileo Galilei. That was because in reality gravity is not the only force acting as an object falls, and the effects of air resistance tend to cause lighter objects to accelerate more slowly. It is something that we have all noticed when comparing the fall rate of a rock and a feather.
Galileo conducted this ingenious experiments at the “leaning” Tower of Pisa and proving by dropping masses of different weights from the top of the tower that gravitational acceleration is independent of the mass of the objects.
Free-fall physics problems are having the assumption of the absence of air resistance. But, in the real world, the Earth’s atmosphere provides some resistance to an object in free fall. Also, particles in the air collide with the falling object, which results in transforming some of its kinetic energy into thermal energy. This results in “less motion” or a more slowly increasing downward velocity.
a free-falling object is an object that is falling under the sole influence of gravity. A free-falling object has an acceleration of 9.8 m/s/s, downward (on Earth). This numerical value for the acceleration of a free-falling object is such an important value that it is given a special name. It is known as the acceleration of gravity - the acceleration for any object moving under the sole influence of gravity. A matter of fact, this quantity known as the acceleration of gravity is such an important quantity that physicists have a special symbol to denote it - the symbol g. The numerical value for the acceleration of gravity is most accurately known as 9.8 m/s/s.
