Trig question for Astronomy Class

Question

Due to continental drift, Africa and South America are moving away from each other at a rate of 4 centimeters per year. The two coasts are currently separated by 5,000 km. Assuming this drift rate is constant, how long ago were the coasts touching? Give your answer in millions of years.

Answer 1

No trig needed

distance = rate*time

distance/rate = time

• distance= 5000 km = (5000 km)*(1000 m/km)*(100 cm/m) = 500,000,000 cm
• rate = 4 cm/year

 

(500,000,000 cm)/((4 cm/year) = ________ years