O movementuniform occurs when a piece of furniture moves in straight line and with velocityconstant. In uniform movement, the mobile travels spacesequals in breaksof equal time.
See too: Introduction to Kinematics
Imagine the following situation: a vehicle that moves in movementuniform, with the speed of 20km/h, will have moved from its initial position in 10km, in a time span of 0,5H (30 minutes). In 1h, this same vehicle will have moved away from its initial position in 20km.
All the movementsuniformsmustto occurinlinestraight, since in this type of movement There is not acceleration. Understand: for a piece of furniture to undergo a change in its direction of travel, it is necessary that a strength act on it by printing a acceleration and making the mobile gain a new velocity component.
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Uniform Motion Formulas
Check out some formulas used to describe uniform motion and understand the meaning of each of its variables:
S - end position of the furniture
s0 — mobile home position
v — mobile speed
t - time interval
v — average speed
S — displacement
t - time interval
References and classification of the movement
In order to correctly define the movement of a body, it is necessary to choose a reference frame. In Physics, we understand that referential is the position in which the observer finds himself. The figure below shows some vehicles moving in different directions along the horizontal direction.
The frame of reference adopted in the figure (marked by point 0) is where the observer is. According to this reference, the cars, on the left, are in positionsnegative, while the cars, on the right, are in positionspositive.
The referential indicates the direction of the movements.
It is important to realize that choosing another reference would imply changing the initial positions of each vehicle and also the classification of their movements. The figure below shows what the chosen framework perceives: for it, the orange car and the silver car, on the left, move away, while the silver car, on the right, approaches it..
We say that when a piece of furniture approaches its reference frame, its movement is regressive. If the mobile moves away from its reference, its movement is progressive. In addition, we attribute to the movementprogressive O signalpositive for speed. For the regressive movement, we use the signalnegative, indicating that the distance between the mobile and its reference decreases with time.
Progressive and Retrograde Motion Video Class
Average speed
The average speed of a rover is given by the displacement ratio (ΔS) in the time interval in which the movement occurred. The displacement (ΔS), in turn, is given by the difference between the positionsFinal and initial of the furniture.
v — average speed
S — displacement
t - time interval
In the formula for the average speed, we call ΔS of displacement. The displacement of a piece of furniture can be easily calculated if we know where it came from (S0 — starting position) and where he arrived (Sf —end position) at the end of the movement, which is delimited by a breakintime (Δt), calculated by the time difference between the momentsFinal and initial (Δt = tf – t0). Check out this formula, in more detail, below:
Speed measurement units
The unit of measure of speed, according to the International System (SI), and the subwaypersecond (m/s). However, there are other common units, such as the kilometerperhour (km/h). It's easy to convert meters per second to kilometers per hour. to do it, just multiply or dividethe speed modulus by factor 3.6, as shown in the following figure:
Examples:
72 km/h / 3,6 = 20 m/s
108 km/h /3,6 = 30 m/s
Mind Map: Uniform Movement
*To download the mind map in PDF, Click here!
Uniform Motion Graphics
We can relate to position of a piece of furniture as a function of time using the graphics. For smooth motion, the graphs of position versus time form straight lines sloping to up or to low, related to movement progressive and regressive, respectively. See an example graph of position versus time for the movementuniformprogressive:
Lookalso:force and movement
In the figure below, we have a graph that represents the position as a function of time for a mobile that performs a movementuniform and regressive (or retrograde).
Position versus time graphs can be used to determine the velocity of the movement. For this, it is enough to notice that the speed of the mobile is given by its tangent, that is, the ratio between the collaredopposite (ΔS) and the adjacent leg to the straight line (Δt).
The velocity versus time graphs for uniform motion, in turn, are straight. parallel to the horizontal axis, of module negative or positive, according to your classification (progressive or regressive). Through the velocity graph, it is possible to calculate the displacement of the rover, to do this, we simply determine the modulus of the area below the line:
In the previous graph, the area painted blue is numerically equal to the area of a rectangle.This area can be calculated using the following formula:
THE - area
B — base edge
H - height
Lookalso: Uniform Motion Graphics
evenly varied movement
O movementevenlymiscellaneous it is a movement whose speed increases or decreases steadily over time. This type of movement is not necessarily straight and is subject to a acceleration constant. If you want to know more about MUV, click on here.
Lookalso: How to solve Kinematics exercises?
Exercises on uniform movement
1) A mobile starts from the starting position S0 = - 15 m and after 12 seconds it is in position SF = 45 m.
a) Determine the average speed of this rover.
b) Determine the hourly function of the rover position.
c) Calculate the mobile position for t = 0 s, t = 1 s, t = 2 s, t = 3 s and t = 4 s. Then build the position versus time graph for that move.
d) Rate the movement described by this piece of furniture.
Resolution
The) To calculate the average speed of this movement, we will use the average speed formula:
Inserting the data provided by the exercise statement, we will do the following calculation:
The result indicates that the mobile moves 5 meters every second.
B) To determine the hourly function of this movement, we just need to identify its initial position and speed. We then substitute these values into the position's hourly function:
Replacing the exercise data, we will have the following hourly position function:
ç) Let's calculate the rover's position, for each of the times mentioned, using its hourly position function:
The graph of this movement is shown below:
d) Analyzing the graph, it is possible to see that the mobile approaches the referential between the instants t = 0 s and t = 3 s, from 3 s onwards, the mobile starts to move away. Therefore, the movement is retrograde between 0 and 3 s and progressive 3 s ahead.
By Me. Rafael Helerbrock
