Matriculation Physics Experiment 5 (malaysia) 20h6w

PHYSICS LAB REPORT SEMESTER 1 EXPERIMENT 5

NAME NO MATRIKS DATE

MUHAMMAD SYAHIR ASYRAF BIN SABRI

MS1712105109 7.8.2017

TEMS CONTENTS MARKS TOPIC

ENERGY

OBJECTIVE

To the law of conversation of mechanical energy

THEORY

From Hooke’s law the stretching force F of an elastic chord is proportional to extension

x as

F=kx

where k is the elastic force constant.

The potential energy stored in the elastic chord given by

U=1/2mv2

If a body of mass m is attached to an elastic chord and extends the latter by x; upon release the body will reach a maximum kinectic energy K.

K=1/2mv2

where v is the maximum speed of the mass.

From the law of conservation mechanical energy,this maximum kinectic energy equals to the elastic potential energy U stored in the elastic chord, that is

NO

NAME

1 2

A trolley with a hook A pair of photogates

3

A timer

4

A metre rule

5

RANGE

SENSITIVITY -

-

(0-100.000000)s

0.000001s

(0.0-100.0)cm

0.1cm

An elastic chord

-

-

6

Two retort stands

-

-

7

A small wooden block

-

-

8

A rail

-

-

K=U

1/2mv 2=1/2kx2

Let x0 be the elongation of the elastic chord when the mass m hangs freely to it, then elastic force constant k is given by

k=mg/x0

substitute into equation 5.5 into equation 5.4, we obtain

v2=g/x0(x2)

Evidently , if we plot a graph of v 2 against x2 , we will get a straight line with a gradient of g/x0

APPARATUS

APPARATUS

PROCEDURE

1. 2.

The apparatus was set up as Figure 5.1. Wooden block is used to raise one of the rail so that the effect of friction is just compensated. The photogates (PB) A and B are arranged at a fixed distance s about 12 cm apart from each other. PG A is ensure placed approximately 1cm from the trolley with the elastic chord not stretched. The trolley is pulled to stretch the elastic chord by an elongation, x within the range of 2cm to 5cm. The trolley is released until it es the two photogates and then record the time t by the timer.

3. 4.

Step (3) repeated two times to obtain the average the value of t. The speed of the trolley, v where v =

5. 6. 7.

Step (4) is repeated for at least five different ascending values of x and tabulate the results. A graph v 2 against x 2 . The gradient of the graph is determined.

8.

The trolley hang freely onto the elastic chord and the elongation,

9.

The gradient of the graph equals to the value of

g x0

x0

calculated is compared. Does experimental result the law of

DATA Experiment A

(cm)

3.0 4.0 5.0 6.0 7.0

Time, t (0.0000 01s) t1

v=s/t ms-1

V2 m2s-1

t2

t average

0.3397 0.3015 0.2650 0.2354 0.1819

0.3733 0.3051 0.2679 0.2235 0.1950

0.3565 0.3033 0.2664 0.2295 0.1885

(x,y)=

[

∑ x2 , ∑ v2

=

[

1.35 1.15 , 5 5

n

n

]

]

X2 (m2)

S=0.12 m X0=0.14 m

0.3366 0.3956 0.4505 0.5229 0.6366

.

is determined of the elastic chord. The value of

conservation of mechanical energy? Write comments.

x

s t

0.1133 0.1565 0.2030 0.2724 0.4053

0.09 0.16 0.25 0.36 0.49

standard deviation;

theo−exp × 100 =¿ theo

Centroid;

g x0

.

=(0.27m2,0.23m2s-2)

0.7109−0.6500 × 100 =8.6 0.7109

Gradient from the graph is; =0.65

From theory;

g 9.81 = x0 0.138 =0.7109

DISCUSSION

In this experiment , the maximum kinetic energy should be equal

K E ¿ U s . The time taken for five different values of length of rubber s chord , x are recorded and is repeated for two times. By using the formula of v = , the speed of the trolley is t g calculated. After that , the theoretical value of 0.7109 is obtained through the formula of . After finishing the xo to the elastic potential energy , which is

experiment , the graph of V 2 against X 2 is plotted and the result gradient is 0.6501. It is not as accurate to the theoretical value due to some errors , such as the railway may be dirty with dirt and dust which increases the friction. This is overcame by clearing the pathway before releasing the trolley. Besides that , it could be that the rubber chord may already be loose before the experiment started. The precaution taken is that an elastic rubber chord is used.

CONCLUSION

Based on the law of conversation of mechanical energy , the theoretical value of 0.7109 is derived. The value which we have calculated from the data of this experiment is 0.6501 means there is a percentage error of 8.6% . Yet , this experiment is still considered a success since the law of conservation of mechanical energy is obeyed eventhough there is a small percentage error.