Science Academy Science Academy Open Inquiry AssessmentOpen Inquiry Assessment

Objective: Objective:

To determine the value of To determine the value of ““gg”” as accurately as possible. as accurately as possible.

William Liu, Leona Lu, Stella So, Alison William Liu, Leona Lu, Stella So, Alison WuWu

ExperimentExperiment1. Measure the value of "g" by using 1. Measure the value of "g" by using

a super ball and meter stick. a super ball and meter stick.

2. Measure the value of "g" by 2. Measure the value of "g" by dropping an object from a high dropping an object from a high distance to the ground.distance to the ground.

Formula Using: Formula Using:

g = 2d/t^2 g = 2d/t^2

d=distance (m)d=distance (m)

t=time (s)t=time (s)

Experiment 1Experiment 1

Materials:Materials:

Digital timer Digital timer

Meter stick Meter stick

White paper tape White paper tape

Whiteboard eraserWhiteboard eraser

A super ball A super ball

Procedure:Procedure:

Stabilize the meter stick against Stabilize the meter stick against the wall to keep it vertical. the wall to keep it vertical.

Drop the super ball from the top.Drop the super ball from the top. When the ball hits the ground, the When the ball hits the ground, the

digital timer should be started by digital timer should be started by the partner who is responsible for the partner who is responsible for timing.timing.

Record the height that the ball Record the height that the ball bounces.bounces.

When the ball hits the ground When the ball hits the ground again, the timer must be stopped.again, the timer must be stopped.

Make measurements.Make measurements. Enter the data into a table. Enter the data into a table.

Measure the value of "g" by using a super Measure the value of "g" by using a super ball and meter stick. ball and meter stick.

Experiment 1-1Experiment 1-1

Experiment 1-1Experiment 1-1Trials #Trials # 11 22 33 44 55 AveragAverag

ee

Time (s)Time (s) 0.70.722

0.70.700

0.80.866

0.80.822

0.80.888

0.80 s0.80 s

Height Height (m)(m)

84.84.55

83.83.77

83.83.55

84.84.22

85.85.22

84.2 84.2 cmcm

The time showing on the timer is twice the time for the ball to The time showing on the timer is twice the time for the ball to fall. Divide the time on the timer by 2 to get "t". "d" is the height fall. Divide the time on the timer by 2 to get "t". "d" is the height the ball bounces to. "g" is the "g" in d = 1/2 g. Therefore g = the ball bounces to. "g" is the "g" in d = 1/2 g. Therefore g = 2d / t22d / t2

g = 2d / t^2 g = 2d / t^2

t = 0.80/2 = 0.40 s t = 0.80/2 = 0.40 s d = 84.2 cmd = 84.2 cm

g = 2(84.2)/(0.40)^2g = 2(84.2)/(0.40)^2g = 1052.5 cm/s = 10.525 m/s^2 g = 1052.5 cm/s = 10.525 m/s^2

Experiment 1-2Experiment 1-2

Experiment 1-2Experiment 1-2

Trials #Trials # 11 22 33 44 55 66 77 88 99 1010 AverageAverage

Time (s)Time (s) 0.80.822

0.840.84 0.90.988

0.80.888

0.70.744

0.70.755

0.70.799

0.70.744

0.80.811

0.80.899

0.824 s0.824 s

Height (cm)Height (cm) 81.81.55

81.581.5 82.82.55

81.81.55

81.81.33

78.78.44

82.82.55

81.81.00

79.79.33

80.80.55

81.0 cm81.0 cm

The calculation is same as Experiment 1-1The calculation is same as Experiment 1-1

g = 2d / t^2g = 2d / t^2

t = 0.824/2 = 0.412t = 0.824/2 = 0.412d = 81.0 cm d = 81.0 cm

g = 2(81)/(0.412)^2g = 2(81)/(0.412)^2g = 954.378 cm/s = 9.54 m/s^2 g = 954.378 cm/s = 9.54 m/s^2

Experiment 2Measure the value of "g" by dropping an object Measure the value of "g" by dropping an object from a high distance to the ground.from a high distance to the ground.

Material:

Object - ball

digital timer

String

meter stick

Scissors

Procedure:Procedure:

Measure the distance to the Measure the distance to the ground by using the string and ground by using the string and meter sticks.meter sticks.

Drop the object several times. In Drop the object several times. In each case, start the timer when each case, start the timer when the object is released and stop the object is released and stop the timer when the object hits the timer when the object hits ground.ground.

Keep track of the time in a table.Keep track of the time in a table.

Experiment 2

Experiment 2

Trials #Trials # 11 22 33 44 55 66 77 88 99 1010 AveragAveragee

Time (s)Time (s) 1.01.055

1.01.044

1.01.066

1.01.044

1.01.077

1.01.055

1.01.033

1.01.088

1.01.011

1.01.099

1.052 1.052 ss

The height is 5.63 m. The height is 5.63 m.

g = 2d / t^2 g = 2d / t^2

t = 1.052 s t = 1.052 s d = 5.63 m d = 5.63 m

g = 2(5.63)/(1.052)^2g = 2(5.63)/(1.052)^2g = 10.17 m/s^2g = 10.17 m/s^2

Sources of Error – Experiment Sources of Error – Experiment OneOne

Floor may not be flat Meter ruler is not perfectly right angled to the floor Blackboard eraser is not perfectly right angled to the meter

ruler Bouncy ball does not bounce in an exact straight line Timing reaction is not perfectly exact due to human reaction

time to when the ball is released and when it hits the ground Hard to read exact measurements of the bouncing ball (even

when using slow motion video playback)

Sources of Error Experiment 2Sources of Error Experiment 2

Floor may not be flat The height of the second flood (distance) is hard to

make exact Timing is based on human reaction time, which is not

100% accurate Ball may not drop straight down

Results

Experiment 1-1: g = 10.525 10.525 m/s^2 m/s^2

Experiment 1-2: g = 9.54 9.54 m/s^2m/s^2

Experiment 2: g = 10.17 10.17 m/s^2m/s^2