Question

an object is projected with intial velocity 28m/s. If maximum height reached by object is 10m .what is direction of intial velocity?

Answer 1

When the particle is going upward vertically, the distance travelled by it is always equal to its displacement. So, in that case the required condition can't be satisfied. When the particle has travelled to the highest point and returning back this condition might be satisfied. Let the highest point it can travel have height hh. And when the particle is, on returning, travelled a distance xx, the required condition is satisfied. So, we can write

Distance travelled, h+x=h+x= 2×2× displacement, h−xh−x

⇒h+x=2(h−x)⇒h+x=2(h−x)

⇒x=h3⇒x=h3

Now, from v2=u2+2asv2=u2+2as, one can write (with g=10m.s−2g=10m.s−2)

0=202−20h0=202−20h

⇒h=20m⇒h=20m

The time taken for achieving this height is given by,

20=20t−1210.t220=20t−1210.t2

⇒t=2s⇒t=2s

The time taken to cover xx is given by,

203=0+1210.t2203=0+1210.t2

⇒t=23√3s⇒t=233s

Therefore, total time taken is

2(3+3√)3

Answer 2

metals are those elements which donate single or double electrons and gain positive charge whereas non metals are those elements which accept electrons and gain negative charge