Value of g

1. Justin Park, Sean Kim, Paul Wang, Derek
Guo

2.  To determine the value of ‘g’ as accurately as
possible.

3.  In a case of free-falling of an object, if the object is
dropping from the known height of the stair with z
ero initial velocity, then the gravity of the object can
be calculated by using the formula,
d=1/2•at2 and the value should reflect closed to the k
nown value of 9.81m/s2.

4.  Measure tape, tennis ball, timer(stop watch)

5. 1. Bring the tennis ball to the certain height on the stair and
measure the height of the tennis ball from the ground.
2. Start the stop watch as soon as you drop the tennis ball
and stop it when it hits the ground.
3. Record your data.
4. Change the height of the dropping level then repeat the
procedure 1-3 six times.

6. Sean
Derek
Justin

8. Paul

9. ??
Tennis ball

12.  We dropped the ball from 7 different displacement
1 2 3 4 5 6 7
d(m) 2.0 2.5 3.0 3.5 4.0 4.5 5.0
t(s) 0.56 0.69 0.73 0.85 0.88 0.92 1.00
t^2(s^2) 0.31 0.48 0.53 0.72 0.77 0.85 1.00
2d(m) 4.0 5.0 6.0 7.0 8.0 9.0 10.0

13. y = 9.024x + 0.984
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10
2d(m)
t2 (s2)
Gravity inquiry - 2d vs t2
Slope = 9.024
9.024 = acceleration =
gravity

14.  Limitation: due to the low displacement, in the case
less than 5m, the time the object hitting the ground
is relatively short. (does not cover human reaction
time to stop the stopwatch.
 Error : (assume that there is no air resistance), the
measure tape was not 100% straight
 Human error : the reaction time.

15.  Hypothesis
 In a case of free-falling of an object, if the object is
dropping from the known height of the stair with
zero initial velocity, then the gravity of the object
can be calculated by using the formula,
d=1/2•at2 and the value should reflect closed to the
known value of 9.81m/s2.
 Our result was pretty close to 9.81m/s2

16.  Conclusion : Throughout this experiment we were
able to find the value of ‘g’ by using the method of
free-falling of a tennis ball from varying heights of
the stairways . Our results, the slope of the best fit
line graph, states that the value of ‘g’ is 9.02m/s2.
As we indicated, the limitation and possible error
sources prevent us from getting precise value of ‘g’,
9.81m/s2.
 Possible suggestion to make this experiment more
precise is to increase the displacement(height) and
to use high-speed camera to measure the time.