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