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Studying uniformly accelerated rectilinear motion

Source: licencja: CC 0.

Badanie ruchu jednostajnie przyspieszonego prostoliniowego

You will learn
  • how to study uniformly accelerated rectilinear motion,

  • how to study uniformly accelerated rectilinear motion using English vocabulary.

Exercise 1
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nagranie abstraktu

Answer the questions.

1. How do we define an accelerated motion?
2. How do we define uniformly accelerated rectilinear motion?
3. Give an example of uniformly accelerated rectilinear motion.

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Ilustracja interaktywna przedstawia trójkąt prostokątny symbolizujący równię pochyłą. Na górze przeciwprostokątnej narysowany jest wózek oznaczony numerem 1. Bok trójkąta prostopadły do podłoża oznaczony numerem 2, bok trójkąta styczny z podłożem oznaczony numerem 5. Kąt między bokiem trójkąta stycznym do podłoża i przeciwprostokątną oznaczony numerem 4, przeciwprostokątna oznaczona numerem 3. Wózek porusza się po równi pochyłej ruchem jednostajnie przyspieszonym. Na ilustracji widoczne są numery, a na nich podpisy. 1. the body under study, e.g. a cart {audio}, 2. height of the inclined plane {audio}, 3. length of the inclined plane {audio}, 4. inclination angle {audio}, 5. base of the inclined plane {audio}.
Motion of the body on an inclined plane
Source: GroMar, licencja: CC BY 3.0.
Experiment
Experiment 1
Research problem
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Studying motion of the cart on an inclined planeinclined planeinclined plane.

Hypothesis
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Movement of the cart on an inclined plane is a uniformly accelerated motion.

You will need
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1. inclined planeinclined planeinclined plane about 2 m long (e.g. wooden board),
2. cart,
3. stopwatch,
4. ruler or measuring tape,
5. paper tape.

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nagranie abstraktu
Instruction

1. Place the inclined plane on the laboratory table (inclination angle: 15°, length: minimum 1,6 m).
2. Put the paper tape along an inclined plane.
3. Place the cart at the top of the inclined plane and let it roll.
4. At regular intervals (every 1 s), mark the position of the cart on the paper tape.
5. Measure the length of the sections covered by the cart (marked on the paper tape).
6. Record the results in the measurement table.

s[m]

t[s]

Δs[m]

Δt[s]

vav=ΔsΔt[ms]

Δvav[ms]

a=ΔvavΔt[ms2]

Hint

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1. Time is measured similarly to the distance measurement, i.e. from the beginning of the body motion. Since the distance travelled is measured every second, the following time values should be: 1 s, 2 s, 3 s, etc.
2. Δs is the distance between consecutive body positions read from the table above.
3. Time is measured every 1 second, so the Δt value is always 1 s.
4. The average speed of a moving body is calculated by dividing the distance and time interval (Δt  =  1 s).
5. The average speed changes are calculated as the difference of its subsequent values. If, on the other hand, we divide them over a period of time, equal to 1 s, we will obtain the value of the accelerationaccelerationacceleration of the cart rolling down the inclined planeinclined planeinclined plane.

Elaboration of results

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nagranie abstraktu

1. Calculate the accelerationaccelerationacceleration for each measurement:

a=ΔvΔt=vfvitfti

where:
vIndeks dolny f - final speed,
vIndeks dolny i  Indeks dolny koniec- initial speed,
Δt - time interval,
tIndeks dolny f - final time,
tIndeks dolny i - initial time.

If we assume that before the body begins to move, it is at rest (vo=0), then after transforming the above formula, we get:

vf=aΔt

2. Compare the results. 
3. Check how much the speed of the cart increases at equal time intervals.
4. Draw a conclusion from the experiment.

Summary

Observation

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The cart speed increases by the same amount at successive identical time intervals.

Conclusions

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- The acceleration with which the cart moved was constant, i.e. it did not change during body motion.
- The motion of the cart is a uniformly accelerated rectilinear motionuniformly accelerated rectilinear motionuniformly accelerated rectilinear motion.
- The speed increases by the same amount at identical time intervals (e.g. every second), and the trajectory of motion is a straight linestraight linestraight line.

Exercise 2
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Determine if the sentences below are true or false.

a) In a uniformly accelerated motion, the speed of the body increases linearly.
b) The final velocityvelocityvelocity for vo=0 is calculated from the formula vf=aΔt.
c) The unit of accelerationaccelerationacceleration may be kms2, kmh2.

Exercise 3
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The body moves with an accelerationaccelerationacceleration of 4 ms2. What speed will it reach after 15 seconds? Select the correct answer.

a) 3,74 ms

b) 60 kmh

c) 3,75 kmh

d) 60 ms

Summary
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  • The uniformly accelerated rectilinear motiouniformly accelerated rectilinear motionuniformly accelerated rectilinear motion is a motion in which the acceleration is constant. This means that the speed increases by a constant value at identical time intervals (e.g. every second), and the trajectory of motion is a straight linestraight linestraight line.

  • The final speed, which the body, having the initial speed vo=0, reached in uniformly accelerated rectilinear motion, we can determine from the formula:

    vf=aΔt

    where:
    vIndeks dolny f[ms] - final speed of the body,
    [ms2] - accelerationaccelerationacceleration of the body,
    Δt - the time interval in which the body moved with the specified acceleration.

  • Characteristic of the uniformly accelerated rectilinear motionuniformly accelerated rectilinear motionuniformly accelerated rectilinear motion is the uniform increase of the speed of the moving body by a constant value at the same time intervals.

Exercises

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Exercise 4
Wersja alternatywna ćwiczenia: The elevator moves with an acceleration of 0,9 ms2. When will it reach the speed of 1,5 ms starting from rest? Możliwe odpowiedzi: 1. 1,667 s, 2. 1,766 s, 3. 1,765 s, 4. 1,350 s
zadanie
Source: GroMar, licencja: CC BY 3.0.
Exercise 5

Determine the average magnitude of acceleration of a cyclist riding a bicycle and when driving on a slope of terrain during time t = 10 s he changed his speed from vi=18kmh to the speed vf=54kmh. Assume that the cyclist's motion is a uniformly accelerated rectilinear motion. Give the result in ms2.

Exercise 6

Write in English what type of motion the falling apple moves and with what magnitude of acceleration.

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Exercise 7
Wersja alternatywna ćwiczenia: Indicate which pairs of expressions or words are translated correctly. Możliwe odpowiedzi: 1. ruch jednostajnie przyspieszony prostoliniowy - uniformly accelerated rectilinear motion, 2. równia pochyła - inclined plane, 3. linia prosta - straight line, 4. szybkość zmiany prędkości - rate of change of velocity, 5. prędkość - acceleration, 6. przyspieszenie - velocity
zadanie
Source: GroMar, licencja: CC BY 3.0.
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Interaktywna gra, polegająca na łączeniu wyrazów w pary w ciągu jednej minuty. Czas zaczyna upływać wraz z rozpoczęciem gry. Jeden ruch to odkrywanie najpierw jednej potem drugiej karty z wyrazem. Każdy wyraz jest odczytywany. Kolejny ruch to odkrywanie trzeciej i czwartej karty. W ten sposób odsłuchasz wszystkie wyrazy. Nawigacja z poziomu klawiatury za pomocą strzałek, odsłuchiwanie wyrazów enterem lub spacją. Znajdź wszystkie pary wyrazów.
Source: Zespół autorski Politechniki Łódzkiej, licencja: CC BY 3.0.

Glossary

acceleration
acceleration

przyspieszenie

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wymowa w języku angielskim: acceleration
inclined plane
inclined plane

równia pochyła

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wymowa w języku angielskim: inclined plane
rate of change of velocity
rate of change of velocity

szybkość zmiany prędkości

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wymowa w języku angielskim: rate of change of velocity
straight line
straight line

linia prosta

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wymowa w języku angielskim: straight line
uniformly accelerated rectilinear motion
uniformly accelerated rectilinear motion

ruch jednostajnie przyspieszony prostoliniowy

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wymowa w języku angielskim: uniformly accelerated rectilinear motion
velocity
velocity

prędkość

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wymowa w języku angielskim: velocity

Keywords

accelerationaccelerationacceleration

inclined planeinclined planeinclined plane

uniformly accelerated rectilinear motionuniformly accelerated rectilinear motionuniformly accelerated rectilinear motion

velocityvelocityvelocity