Question

The displacement of a seconds hand of a clock of length 7 cm in 15 seconds is [ ]

a) 7 cm b) 7 2 cm c) 14 cm d) 21 cm​

Answer 1

Given length of second hand = 7 cm

time taken = 15 sec

angle made = 90°

so,

displacement = 7√2 cm

Answer 2

Answer:7√2

Explanation:

The length of seconds arm is the radius of the circle/clock. It rotates for 15 secs meaning that it has rotated at 90°. Imagine this as a isocelus triangle. The length of seconds arm is equal to the sides of the triangle. To find the hypotenuse, use pythagoras theorem.

7^2 + 7^2 = h^2

2 * 7^2 = h^2

h = √(2*7^2)

h = 7√2.