Reaction time tests can be used to assess an individual’s hand-eye coordination. One test involves catching a 1 metre ruler and measuring the distance, d in metres, that the ruler travelled before being caught. The reaction time t seconds is then calculated using the formula:

= √2d/9.8

(a) Simplify the expression 2d/9.8 under the square root sign to d/?

(b) Calculate the reaction time if the distance the ruler fell before being caught was
44cm.

(c) Make d the subject of the equation, remembering to use your simplified version of
2d/9.8 which you found in part (a).

(d) Use your equation from part (c) to find the distance the ruler should fall before being caught if t is half the value you found in part (b), i. e. half the time taken to catch the ruler when it fell 44 cm.