Download - instructional materialabout free fall
“WIN IT OR
LOSE IT”
Mechanics:The teacher will present questions by
category, each category has corresponding points.
You are going to write your answers on the cardboard, and given only 5 seconds to answer. After five seconds, wait for the teacher to instruct you to raise your cardboards. The winning group will be given a prize.
Arrange me please!!!1st category
gehith
height
(5pts)
2nd category
Point Me!
UPWARD
DIRECTION
(5pts.)
3rd categoryGive me what I need!
the acceleration of a freely falling object in the absence of air resistance.
9.8 m/s2(5pts.)
4th category
4 pic’s1 word
GRAVITY
(5pts)
5th category
Anything Under the sun
(5pts.)Ball
Congratulations!!!
Free-Fall Motion
Free Fall Free Fall – An object in free fall falls at a
constant acceleration towards the surface of a planet neglecting air resistance.
Free Fall AccelerationFree fall acceleration is due
to gravity and is denoted with the symbol “ag”.• At the Earth’s surface, the
free fall acceleration is approximately -9.8 m/s² or about 32 ft./sec²
VelocityObjects Velocity in Free Fall
• Upward motion – Positive Velocity• Downward motion – Negative Velocity
Objects Motion During Free Fall
An object thrown straight up will have a positive velocity and a negative acceleration.
An object falling towards the earth will have a negative velocity and a negative acceleration.
Motion of an Object in Free Fall: Velocity
The object has a positive velocity when thrown upward, and it becomes zero when it reaches its maximum height, during free- fall, its velocity will be negative and as soon as it reaches the same point from where it was released its velocity will be equal to the initial velocity and the sign will be negative showing the direction.Example: If I throw a ball upward with a velocity of 15m/s, I will catch it in my hand with a velocity of -15m/s when it comes back down. As long as the origin doesn’t change.
TimeThe time for the object to go up is the same as it falls.• Example: If I throw an object upward and it takes 5 seconds
to reach maximum height. It will take 5 seconds to come back down to its original position of where it was thrown.
“You raise
me up”
ACTIVITY #3
Objectives: Determine the initial velocity of a ball thrown
upward; Record the time for the ball to reach the ground; Record the time for ball to reach its maximum
height; and Calculate the maximum height reached by the ball
thrown vertically upward.
Procedure:1.Throw the ball vertically upward in the
air as hard as you can in an open space.
2. Using your stopwatch, ask your classmate to record the total time the ball remains in the air. Get the time of the ball from point of release to its maximum height by the dividing the total time into two. Record your data. (perform 3 trials)
3.Calculate the initial velocity of the ball using the formula vi =vf +agt. Use - 9.8m/s2 for ag.
4.Solve for the maximum height reached by the ball using h=vit + ½ agt2. Use -9.8m/s2for ag. Record your data.
Post DiscussionQ1. What do you think happens to the speed of the ball as it reaches its maximum height?Answer: The ball stops momentarily at its maximum height.
Q2. What will happen to the ball’s velocity as it falls further below the point of release?Answer: The velocity increases as it falls further below the point of release.
Positive velocity since the ball is moving upward.
Negative Velocity since the ball is moving downward.
When ball reaches maximum height, the velocity = 0
Acceleration is a constant and is always -9.8m/s2
“What goes up
must come down”
PUSHPray Until
Something Happens
Short quiz: By group
Choices:a. 9.8 m/s
b. -9.8 m/s2
c. 0 m/s
d. cannot be determined
e. 10 m/s2
f. -10 m/s
g. 0 m/s
Direction: Write the letter of your chosen answer
Necida throws a ball straight up with an initial velocity of 10 m/s.
Q1What is its velocity at the highest point?
Short quiz: By group
Choices:a. 9.8 m/s
b. -9.8 m/s2
c. 0 m/s
d. cannot be determined
e. 10 m/s2
f. -10 m/s
g. 0 m/s
Direction: Write the letter of your chosen answer
Necida throws a ball straight up with an initial velocity of 10 m/s.
Q2 What is its acceleration at the highest point?
Short quiz: By group
Choices:a. 9.8 m/s
b. -9.8 m/s2
c. 0 m/s
d. cannot be determined
e. 10 m/s2
f. -10 m/s
g. 0 m/s
Direction: Write the letter of your chosen answer
Necida throws a ball straight up with an initial velocity of 10 m/s.
Q3 What is its velocity when it returned to the elevation from where it was thrown?
Short quiz: By group
Choices:a. 9.8 m/s
b. -9.8 m/s2
c. 0 m/s
d. cannot be determined
e. 10 m/s2
f. -10 m/s
g. 0 m/s
Direction: Write the letter of your chosen answer
Necida throws a ball straight up with an initial velocity of 10 m/s.
Q4 What is its acceleration just before it hits the ground?
Short quiz: By group
Choices:a. 9.8 m/s
b. -9.8 m/s2
c. 0 m/s
d. cannot be determined
e. 10 m/s2
f. -10 m/s
g. 0 m/s
Direction: Write the letter of your chosen answer
Necida throws a ball straight up with an initial velocity of 10 m/s.
Q5 . After 1 second what is the acceleration of the ball?
Assignment1. What is motion in two dimensions?2. Give the meaning of trajectory and range.
References: Science grade 9 Unit 4 pp. 15-27 www.google.com