Question

An object is placed at a distance of 4 centimetres in front of a concave mirror whose for length is 5 centimetres where is the image formed​

Answer 1

Given:-

• Object distance , u = -4cm

• Focal length ,f = -5cm

To Find:-

• Image - distance

Solution:-

By using mirror formula

• 1/v +1/u = 1/f

Substitute the value we get

→ 1/v = 1/f - 1/u

→ 1/v = 1/(-5) - 1/(-4)

→ 1/v = -1/5 + 1/4

→ 1/v = -4+5/20

→ 1/v = 1/20

→ v = 20cm

∴ The image distance is 20cm.

Answer 2

Answer:

Initial velocity ,u = 10m/s

Acceleration ,a = 8m/s²

Final velocity ,v = 40m/s

So By using 3rd equation of motion

• v² = u² +2as

Substitute the value we get

→ 40² = 10² +2×8×s

→ 1600 = 100 + 16×s

→ 1600-100 = 16×s

→ 1500 = 16×s

→ s = 1500/16

→ s = 93.75m

The length of Runway 93.80m