SCIENCE 7 Q3 Week 2
SCIENCE 7 Q3 Week 2
SCIENCE 7 Q3 Week 2
THIRD QUARTER
Module 2
https://www.carbase.co.uk https://www.needpix.com
https://michaelmowsblog.wordpress.com/2011/09 https://www.illustrationsource.com
“Acc-hilirating”
JOEL P. BAUTISTA
Writer
To the Learners
This module was made to help you understand lesson regarding motion. For you to
Expectations
be able to achieve the goals of this module, you should take note of the following guides:
1. Find a special place in your home that will make you comfortable while doing this
module.
2. Read and understand all the instructions in this module.
3. Jot down the key ideas that you encounter in this module in your notebook.
4. Follow the directions in the activities diligently.
5. Answer all the questions and complete the tasks that are included in the activities.
6. Approach your parents or guardians to guide you in doing the activities.
7. Enjoy while learning.
The Writer
Expectations
After doing this module, you are expected to:
1. Define acceleration.
2. Describe motion in terms of acceleration.
3. Calculate the acceleration of the moving object
Pretest
Direction: Read and understand the questions carefully. Write the letter of the best
answer on the space provided before each number.
_______ 1. How can you say that the moving object is accelerating?
A. When its speed is changing
B. When its direction is changing
C. When both speed and direction is changing
D. All of the above
________ 2. Which of the following situation shows that there is acceleration?
A. A stalled car.
B. A man jogging in place.
C. A car with decreasing speed and come to stop.
D. A train moving at constant speed toward North.
_________ 3. What is the SI unit of acceleration?
A. m B. s C. m/s D. m/s2
__________ 4. A car is accelerating at the rate of 5 m/s/s, what does it mean?
A. The car travels at constant speed of 5 m/s.
B. The car is covering 5m distance in every second.
C. The speed of the car increases by 5 m/s in every second.
D. The speed of the car decreases by 5 m/s in every second.
_________ 5. What is the acceleration of the car whose speed increases from 20 m/s to
50 m/s in 5 seconds?
A. 6 m/s2 B. 30 m/s2 C. 70 m/s2 D. 75 m/s2
Looking Back
Direction: Match Column A to the Column B. Write the letter of your answer on
the space provided before each number.
A B
_____ 4. The distance covered by the object per unit time. D. motion
1
Brief Introduction
Have you experienced riding a car? How do you describe the usual motion of it
during your trip? Does the car travel at constant speed? Does the car move in only one
direction? An object in motion usually has changing speed even if it is moving along a
fixed direction. Its speed increases at the start and decreases when about to stop. The
direction of motion is also changing, since a car needs to change lane, go on the curve
path or turn right or left. Whenever the speed, direction, or both speed and direction
change, the velocity of the car also changes. This change in velocity with the
corresponding change in time is known as acceleration.
Change in velocity
Acceleration=
Change in time
a= ΔV_ = vf – vi
Δt tf - ti
where Δv is change in velocity which is equal to the difference between the final velocity
(vf ) and initial velocity(vi); and Δt is the change in time which is equal to the difference
between final time(t f ) and initial time(ti).
The unit of acceleration is the unit of velocity divided by the unit of time. If the Δv is in
m/s and Δt is in seconds, then the unit for acceleration is
m/s
s = m/s/s = m/s2 .
Suppose that a car starting from rest gains a velocity of 5 meters per second at
the end of first second, and then 10 meters per second at the end of 2 seconds, and 15
meters per second after 3 seconds. From the equation of acceleration, the average
acceleration during the first three seconds is
vf – vi = 15 m/s – 0 15 m/s
a = = = 5m/s/s or 5 m/s2 .
tf - ti ( 3-0 )s 3s
The result tells that the velocity of the car increases at the rate of 5 m/s every
second. You should be careful about the difference between the unit of velocity and the
unit of acceleration. If the change in velocity is in km/hr and the unit in time is in
seconds, the unit of acceleration is km/hr/s which is also equivalent to km/hr.s.
vf – vi –40 km/hr
a= or vf – vi = 0 – 40km/hr =
tf - ti t 2s 2s
= -20km/hr/s or - 20 km/hr.s.
This means that the velocity of the car decreases by 20 km/hr for every second.
2
Is it possible that the car accelerates without any change in its speed? Yes, cars
accelerate when the direction changes, for example, if the car is moving at constant
speed but around a curve path. Although in this case there would be no change in
speed, but there would be a change in direction and therefore there is a change in
velocity. This change in velocity is acceleration.
Direction: Draw happy face if the picture shows acceleration and sad face
if it is not on the space provided.
1. Cars slowing down before coming to stop. 6. Earth revolving around the sun.
https://www.sciencephoto.com
https://www.carbase.co.uk/
____________________________________ ___________________________________
2. Cars moving in a curved path at constant 7. An apple falling from the tree.
speed.
https://pngtree.com
http://www.clipartbest.com
___________________________________________ _____________________________________
3.A train maintaining constant speed and direction. 8. Stalled car
https://www.needpix.com https://www.shutterstock.com
___________________________________
_________________________________________
3
4. A boulder rolling down the hill. 9. Car driving uphill.
https://www.illustrationsource.com https://michaelmowsblog.wordpress.com/2011/09
___________________________________________ ___________________________________
https://www.vectorstock.com
http://clipart-library.com
___________________________________________ ____________________________________
Direction: Study the given data and answer the question ask.
A. The velocity of the car per unit time is shown in the table below.
Velocity(m/s) 0 15 15 40 60 0
Time (s) 0 1 2 3 4 5
4
6. At what time interval does the car reach the highest acceleration?
_________________________________________________________________________
7. What is the highest acceleration of the car?
_________________________________________________________________________
8. What is the lowest acceleration of the car?
_________________________________________________________________________
9. At what time interval did the car attains the lowest acceleration?
_________________________________________________________________________
10. Based on the given data, how do you describe the motion of the car in the
whole trip?
Activity 3. Solve!
A. Direction. Compute for the acceleration given following data.
1. 0 m/s 15 m/s 3s
2. 20 m/s 70 m/s 10 s
5. 25 km/hr 55 km/hr 30 s
5
4. In 2.5 seconds a train decreases its speed from 50 km/hr to 40 km/hr.
What is the acceleration?
5. The car starting from rest accelerate at 2m/s2, what is its speed after 10
seconds?
Remember
• Acceleration is the rate of change in velocity of an object.
• The acceleration equation is
Vf – vi
a = Δv =
Δt tf - ti
wherein:
Δv is the change in velocity vi is the initial velocity vf is the final
velocity
Δt is the change in time ti is the initial time tf is the final time
Direction. Identify the part/s that serves as accelerator or makes the bicycle to
accelerate. Give your reason.
Frame
Wheel
Pedal
http://clipart-library.com/bicycle-clip-art.html
6
ACCELATOR REASON
Posttest
Direction: Read and understand the questions carefully. Write the letter of the
best answer on the space provided before each number.
_______ 2. The toy when whirled around has a constant speed and moved in a circular
path. Which of the following assumption(s) is/are TRUE?
______ 4. In which of the following cases does the object have negative acceleration.
A. when the velocity increases C. when the velocity does not change
B. when the velocity decreases D. Insufficient data
_______ 5. What is the acceleration of the truck that changes its velocity from 30 m/s
to 45 m/s in 6 seconds?
A. 15 m/s2 B. 10 m/s2 C. 5 m/s2 D. 2.5 m/s2
7
Reflection
Direction: Write the things that you know before and after studying the module about
acceleration.
BEFORE AFTER