in love with FREE FALL FORM 4 BY: PHYSICS & MATHEMATICS TEAM PHYSICS to
CLASS: FORM 4 SUBJECT: PHYSICS DATE: DECEMBER 2023 TOPIC: 2.3) FREE FALL MOTION LESSON OBJECTIVES: At the end of the lesson, students are able to: Explain free fall motion and gravitational acceleration by providing examples. Determine the value of gravitional acceleration by conducting an experiment. Solve problems involving the Earth’s gravitational acceleration for objects in free fall.
LEARNING OBJECTIVE At the end of the lesson, students are able to: 2.3.1 Explain free fall motion and gravitational acceleration by providing examples. 2.3.2 Determine the value of gravitational acceleration by conducting an experiment. 2.3.3 Solve problems involving the Earth’s gravitational acceleration for objects in free fall. 2.3 Free Fall Motion
FREE FALLING A motion under force of gravity as the only force acting on the moving object Free falling object does not experience the action of other forces Video on free fall SUGGESTED ACTIVITY: Show an object falling with and without air resistance. Use objects such as crumpled paper and eraser
Motion of falling objects in air. Feather Metal ball Motion of falling objects in vacuum. Feather Metal ball In daily life, heavier object seems to reach the ground faster due to the presence of other forces such as air resistance Video on object falls in different condition
Gravitational accelaration Gravitational acceleration of an object is due to the pull of the gravitaional force with the unit of ms^-2 Gravitational acceleration does not depend on the mass of the moving object. The magnitude of gravitational acceleration is 10ms^-2 DETERMINING THE VALUE OF GRAVITATIONAL ACCELERATION The value of gravitational acceleration can determined by: Measuring the acceleration of heavy object such as steel ball in a physics laboratory. A photogate system and an electronic timer. Acceleration due to gravity
PROCEDURES EXPERIMENT APPARATUS A steel ball, electromagnetic release, two photogates, electronic timer, tripod stand and container to catch steel ball released. EXPERIMENTAL SETUP (1) Place the second photogate to the distance of 30m away from the first photogate. CALCULATION & DATA COLLECTION AIM: conduct PHOTOGATE EXPERIMENT to determine the value of Earth’s gravitational acceleration, g. (2) Ensure the steel ball can fall through both photogates into the container. (3) Release the steel ball from the electromagnetic release. (4) Record the time when the steel ball passing through the first photogate as t1 and the second photogate as t2 in Table. (5) Repeat steps 1 to 4 with distances 40cm, 50cm, 60cm and 70cm. COMPARE! The experimental & theoretical value of gravitational acceleration, g Calculate the value of g using following formula: 1 2 3 4 Video of experiment
velocity (ms^-1) 0 v Before being released, the velocity of the object is zero. The object is stationary When the object released, velocity object increase uniformly. Gradient of velocity-time graph = acceleration This acceleration is known as gravitational acceleration VELOCITY-TIME GRAPH stationary object velocity = 0 ms^-1 velocity increase Time (s) MOTION GRAPHS OF OBJECT EXPERIENCING FREE FALL
Displacement (m) 0 v Before being released, the displacement of the object is zero The object is stationary DISPLACEMENT-TIME GRAPH Once the object released, it falls with a low velocity. This can be seen in the small value of the gradient During free fall, the object falls with a higher velocity than its initial velocity This can be seen in the greater value of the gradient of the graph. stationary object velocity = 0 ms^-1 velocity increase MOTION GRAPHS OF OBJECT EXPERIENCING FREE FALL Time (s)
Displacement (m) 0 At the maximum height, the velocity of the object is zero VELOCITY -TIME GRAPH When thrown upwards, the object starts to move with a velocity of V ms^-1. The velocity of the object decreases as the object move upwards This gradient of the velocity-time graph is negative Time (s) maximum displacement = 0 ms^-1 velocity decreasing MOTION GRAPHS OF OBJECT MOVING AGAINTS GRAVITATIONAL FORCE (ANTIGRAVITY) velocity = V ms^-1 V
Maximum displacement, zero velocity The object will momentarily stop before falling back downwards Displacement (m) 0 Once thrown upwards, the object moves with a velocity, V ms^-1. At the same time, the displacement of the object changes. DISPLACEMENT -TIME GRAPH The object moves upwards with decreasing velocity Time (s) maximum displacement = 0 ms^-1 velocity decreasing MOTION GRAPHS OF OBJECT MOVING AGAINTS GRAVITATIONAL FORCE (ANTIGRAVITY) velocity = V ms^-1 V
The value of gravitational acceleration, g changes from one place to another. For example: The value at the equator=9.78ms^-2 The value at the Earth’s pole=9.83ms^-2. This happens due to the shape of the Earth is actually not perfect.
SOLVE PROBLEMS INVOLVING FREE FALLING OBJECT v = u + at s = ut + ½at² v² = u² + 2as FORMULA Choose the formula that needed to be used wisely! 1.Object falls: a = -g = -10m/s² 2.Object thrown upward: a = -g = -10m/s² 3. At the highest position: v = 0m/s 4. Falls downward: v is negative. 5. Thrown upward, v is positive.
FORMATIVE ASSESSMENT A feather, a coin and marble was dropped simultaneously in a vacuum. Which object will lands first? 1. A. All three objects B. Coin and feather C. Coin and marble D. Marble and feather Learning objective: Students are able to apply free fall motion and gravititional acceleration concept from example provided 2. How would acceleration-time graph looks like when a coconut falls from a tree? A. C. D. B.
ANSWER & REASONING 1. A.All object In vacuum, all object have the same gravitational acceleration which is 10ms⁻². This gravitational acceleration does not depend on mass of an object. Motion of falling objects in air. Feather Metal ball Motion of falling objects in vacuum. Feather Metal ball 2. A. When a body is falling under the sole influence of gravity wherein it is being acted upon only by the force of gravity is called a freely falling body. There are two important notions that model free falling: (I)The rate of change of velocity remains the same. (II)All freely falling bodies on Earth accelerate at a rate of 10ms⁻² downwards.
Learning objective: Students are able to solve problems involving the Earth’ s gravitational acceleration for objects in free fall 3. A brick falls from a height of 10m. Calculate time taken for the brick to reach the ground. A. 0.5s B. 0.7s C. 1.0s D. 1.4s 4. What is the velocity of an object that has been falling freely in a vacuum for 2 seconds? A. 10 m/s B. 20 m/s C. 30 m/s D. 40 m/s CALCULATION:
ANSWER & REASONING Refer formula in page 11
Learning objective 1: Students are able to explain the concept of free fall motion. A golf ball and a piece of paper are held at the same height and dropped simultaneously. 1. a) Which object will hit the floor first? Why? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . b) Repeat the experiment with a golf ball and a piece of crumpled paper. Which object will hit the floor first? Why? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.Diagram shows a stroboscope photo of a ball falling freely and velocity against time graph and its motion. a) Observe the photo. Explain the velocity of the ball. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . b) What can you deduce from the gradient of graph v-t? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c) Explain the motion of the ball. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Learning objective 2: Student are able to determine the value of gravitational acceleration by conducting the experiment. a) What is the type of motion if it falls under attraction of gravity? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . b) Compare the value of acceleration due to gravity from the activity to the actual value. Give a reasonable reason for the difference between the two values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. In a photogate experiment, a steel ball is relased from the electromagnetic release.
Question 1 a) golf ball will hit the floor first. Because there is less air resistance causing the golf ball to fall faster than the piece of paper. b) this time, both golf ball and crumpled paper will fall and touch the ground at the same time, because the mass is ignored and both objects fall with the same gravitational acceleration. Question 2 1) the velocity of the ball increases with time. b) the gradient of the graph is the acceleration of the ball. the acceleration is constant every time. c) the ball falls with constant acceleration as the velocity increases uniformly with time. Question 3 1) free fall motion 2) the experimental value for gravitational might be differ from the actual value, g = 9.81ms^-2. This happens due to the presence of air resistance during the fall. Answers:
in love with FREE FALL FORM 4 STRUCTURES AND DEVELOPMENT OF PHYSICS MODULE PHYSICS to
MODULE OBJECTIVES At the end of the lesson, students should be able to: Explain free fall motion and gravitational acceleration by providing examples. Determine the value of gravitational acceleration by conducting an experiment. Solve problems involving the Earth’s gravitational acceleration for objects in free fall. Theme: Newtonian Mechanics Chapter 2: Force and Motion Sub-Topic: FREE FALL MOTION
PROBLEM STATEMENTS Students might ignore the application of the inertia concept in daily life. Students might thought heavier object falls faster than lighter object. Student might confused the with and without air resistance situations. 1 2 3
ADDIE MODEL 01 02 03 ANALYZE DESIGN DEVELOP
ANALYZE
PRIOR KNOWLEDGE AUDIENCE Form 4 students in high school. Students should know the concept of acceleration from subtopic using stroboscope from subtopic 2.2 Linear Motion. Student should familiar in using photogates and ticker tapes. Students should understand with the terms acceleration, velocity and gravity. ANALYZE
At the end of the lesson, students should be able to: Explain free fall motion and gravitational acceleration by providing examples. Determine the value of gravitational acceleration by conducting an experiment. Solve problems involving the Earth’s gravitational acceleration for objects in free fall. OBJECTIVES ANALYZE
DESIGN
EXPLORATION Computer or smart phone INDUCTION Multimedia presentation (videos) DESIGN (MEDIA, TECHNOLOGY & LEARNING TOOLS) INVOLVEMENT Textbook Comprehensive notes provided in module Crumple paper (light object) Eraser (heavier object)
ASSESSMENT Photogate system Steel ball Tripod stand Electronic timer Electromagnetic release Container to catch steel ball released Multimedia presentation (video) EXPERIMENTATION DESIGN (MEDIA, TECHNOLOGY & LEARNING TOOLS) Pencil Calculator Set of questions provided in module
(TOOLS & APPARATUS FOR EXPERIMENT)
EXPLORATION Students watch videos related to free fall motion (2 videos with QR code provided) to attract their attention on the introduction of the free fall motion concept. INDUCTION DESIGN (STRUCTURE OF ACTIVITIES) Qualitative explanation using comprehensive and interesting notes on the motion of an object falling in a uniform gravitational field. INVOLVEMENT Student self-conduct a simple activity for an object falling with and without air resistance. Use crumple paper (light) and eraser (heavier) to observe the comparison.
ASSESSMENT EXPERIMENTATION DESIGN (STRUCTURE OF ACTIVITIES) Watch video of photogate experiment being carried out following correct procedures and setup, using QR provided in module. Students conduct a real-time photogate experiment in the laboratory - to compare experimental and theoretical gravitational accelerations value, g. Formative assessment will be provided in the module by giving questions to enhance and evaluate students’ understanding on free fall motion and gravitational acceleration concept.
DEVELOP
EXPLORATION Computer or smart phone Multimedia presentation (videos) INDUCTION DEVELOP (LEARNING TOOLS & STRUCTURE OF ACTIVITIES) QR for videos on free fall motion are provided in the module, and can be played straight from computer or smart phone. Textbook Comprehensive notes provided in module Qualitative notes and formula of free fall motion and gravitational accelerations concept are provided in the module.
EXPERIMENTATION DEVELOP (LEARNING TOOLS & STRUCTURE OF ACTIVITIES) Students use two different object which are crumpled paper and eraser. They will drop the both object at the same height and measure the time taken for both object arrived at bottom Crumple paper (light object) Eraser (heavier object) Lab experiment using photogate In this experiment, student will roll a ball down a ramp and determine the ball’s velocity with a pair of Photogates. Measure the velocity of a ball using two Photogates. INVOLVEMENT
Answering the formative assestment ASSESSMENT SESSION DEVELOP (LEARNING TOOLS & STRUCTURE OF ACTIVITIES) From the lesson, students can test their understanding by answering the assestment. Write a laboratory experiment report. Students undergo laboratory experiment involving photogate and record the data. From data students need to write a full lab report.