1. A body falls freely from rest for 6 seconds. Find the distance travelled in the last two seconds. Take g=9.8 m/s
2. A body is projected vertically upwards with a velocity of 20 m/s. Find the distance travelled by it in 3 seconds. taking g=10m/s

1.

Here,

t = 6 s

u = 0

Distance traversed in 6 s

s₁ = ut +  ½gt²

  = ½ × 9.8 × 6²

  = 176.4 m

Let t₁  be the time elapsed before last two seconds

t₁ = 6 – 2 = 4 s

Distance traversed in 4 s

 s₂ = ut +  ½gt²

  = ½ × 9.8 × 4²

  = 78.4 m

Distance covered in last two seconds

= s₁ – s₂

= 176.4 – 78.4

= 98 m

2.

Here,

u = 20 ms^-1

g = 10 ms^-2

t = 3 s

s = ut + ½ (-g)t²

=> s = 20×3 – ½×10×3²

=> s = 60 – 45

=> s = 15 m

Distance traversed = 15 m