Textbook Page 80 Question #28

Question: The period, t, in seconds, of a pendulum is the time it take for a complete swing back and forth. The period can be calculated from the length, l, in metres, of the pendulum using the formula t = *square root* of 41. Determine the period of a pendulum with each of the following lengths. Express each answer to the nearest hundredth of a second. 

A) 1.6 m

l = 1.6 m
t = *square root* 4l 
t =  *square root* 4(1.6) 
t = *square root* 6.4 
t = 2.529

Round to nearest hundredth of a second: 2.53 s.

B) 2.5 m

l = 2.5 m
t = *square root* 4l 
t = *square root* 4(2.5)
t = *square root* 10
t = 3.1622 

Round to nearest hundredth of a second: 3.16 s.

C) 50 cm

l = 50 cm
t = *square root* 4l
t = *square root* 4(0.5)  << To get 0.5, you change 50 into a decimal, 50 divided by 100 gives you 0.5. 
t = *square root* 2
t = 1.414 

Round to nearest hundredth of a second: 1.41 s.