A ball, dropped vertically, falls d metres in t seconds. d is directly proportional to the square of t. The ball drops 45 metres in the first 3 seconds. How far does the ball drop in the next 7 seconds?

If d is directly proportional to the square of t, we write this as d= kt2 , where k = the proportionality constant which we must find. Substitute in the values given in the question into our equation to get 45= k (32) and hence 45= 9k , so k=5. Now we know the value of k, we can find out how far the ball travels in a further seven seconds. We cant isolate these seven seconds using our equation, so instead use the value t=10 (3+7 seconds), to find d after 10 seconds of falling. d= 5(102) = 500. If the ball has gone 500m after 10 seconds, and we know it had travelled 45 of those metres in the first 3 seconds, we find how far it went in the 7 seconds after by doing 500 - 45 = 455 m.

KL
Answered by Katie L. Maths tutor

20799 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Factorise 12x^2 - 20x + 3


Use approximations to 1 significant figure to estimate the value of 0.101 x (51.2)^2 / (3.96)^1/2


What is 12x^6 / 7 divided by 4x^2 / 5 ?


Lewis wins £360 in a prize draw. He gives 15% to charity and puts 3/8 into his savings. The rest he uses to buy a bike. How much of the money has Lewis got left for this bike? Note: do not use a calculator


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning