Question

b. 110 km/h into m/sec (hint: use your answer to (a) and continue.)
c. 150 rpm into revolutions per second (1 min = 60 sec)
d. 150 rpm into seconds/revolution (hint: use your answer to (c) to solve this one.)

Explanation:

Step1: Convert km/h to m/s for part b

1 km = 1000 m and 1 h = 3600 s. So, to convert 110 km/h to m/s, use the conversion factor $\frac{1000}{3600}$.
$110\times\frac{1000}{3600}=\frac{110000}{3600}=\frac{275}{9}\approx30.56$ m/s

Step2: Convert rpm to revolutions per second for part c

Since 1 minute = 60 seconds, to convert 150 rpm to revolutions per second, divide by 60.
$150\div60 = 2.5$ revolutions per second

Step3: Convert rpm to seconds per revolution for part d

If there are 2.5 revolutions per second from part c, then the number of seconds per revolution is the reciprocal of the number of revolutions per second.
$1\div2.5=\frac{1}{\frac{5}{2}}=\frac{2}{5}= 0.4$ seconds per revolution

Answer:

b. $\frac{275}{9}\approx30.56$ m/s
c. 2.5 revolutions per second
d. 0.4 seconds per revolution