Question

An object is thrown vertically upwards and reaches a height 20m. Calculate. A)the velocity of the object. B)the time taken to reach the highest point.(g=10m/s^2

Answer 1

v = 0m/s

g = -10m/s²

s = 20m

we know,

v²=u²+2as

0 = u²+2(-10)20

0 = u²-400

400 = u²

u = √400 = 20m/s

Velocity of object = 20m/s

We know,

s = ut+½at²

20 = 20t+½(-10)t²

20 = 20t-5t²

5t²-20t+20 = 0

=>5t² -10t-10t+20 = 0

=>(5t²-10t)+(-10t+20) = 0

=>5t(t-2) -10(t-2) = 0

=>(5t-10)(t-2) = 0

=>5t-10 = 0

=>5t=10

=> t = 2

also,

t-2 = 0

t=2

So,

The time taken to reach the highest point = 2seconds

Cheers!