A motorcycle has an initial speed of u m/s. It accelerates to a speed of 1.2u in 10 seconds. The motorcycle then travels at a constant speed of 1.2u m/s for 15 seconds. Assuming that the acceleration is constant, express the total distance, D in metres, traveled by the motorcycle.

Step-by-step explanation:

A motorcycle has an initial speed of u m/s. It accelerates to a speed of 1.2u in 10 seconds

V = U + at

1.2u  = u  + a*10

=> a = 0.02u

S= ut + (1/2)at²

Distance in 1st 10 secs

S = u(10) + (1/2)(0.02)(10)²

=> S = 10u + u

=>  S = 11u  m

Constant speed 1.2u for 15 secs

S = 1.2u * 15

=> S = 18u m

Total Distance Covered d  = 11u + 18u = 29u  m

answer: 7 x 2/5 = 2.8 hours, is your answer. your welcome! : 3

step-by-step explanation: first work out how long it took to hose 1/7 of the lawn which is 2/5 hours. times that by 7 to get the whole lawn.

sorry i don't know the other answer. i didn't learn what a proportional relationship is.