If speed (v) and time (t) are related as t²-10vt+10000=0; then what can be the values of v?

a) All values more than or equal to 20 units

b) All values less than 20 units

c) All positive values are possible for v

d) No value of v can satisfy the given expression

Dear  Abhingya Patra

t²-10vt+10000=0

this equation is quadretic in time.

since time t is real positive value

solve this equation for t

 t = {10v ± √(10v)² -4*1*10000}/2

    ={10v ± 10√v² -400}/2

    =5v ± 5√(v² -400)

for real value of t

v² -400 ≥0

(v-20)(v+20) ≥0

 V ≤-20  or v≥20

but negative value of t will give negative time which is not possible

so v≥20 is the solution

Please feel free to post as many doubts on our discussion forum as you can.
 If you find any question Difficult to understand - post it here and we will get you the answer and detailed solution very quickly.
 We are all IITians and here to help you in your IIT JEE  & AIEEE preparation.

 All the best.
 
Regards,
Askiitians Experts
Badiuddin