Question

The distance xm travelled by a particle in time t seconds is described by the equation x = 10 + 12tsquare, Find the average speed of the particle between the time interval t = 2s and t = 5s
A. 60 ms-1
B. 72 ms-1
C. 84 ms-1
D. 108 ms-1​

Answer 1

After 2 seconds the particle will be in position

$x(2)=10+12\cdot 2^2=10+12\cdot 4=10+48=58$

After 5 seconds the particle will be in position

$x(5)=10+12\cdot 5^2=10+12\cdot 25=10+300=310$

So, the particle will travel

$310-58=252$

meters in 3 seconds, for an average speed of

$\dfrac{252}{3}=84$