Question

Assuming consatant retardation of metal ball moving inside water thr ball loses 25% of its speed in 35 cm in a straight line . How much further will it travel before stopping ?

Answer 1

Answer:

Explanation:Let initial velocity of bullet is u ,

A/C to question,

bullet loses25% of its speed while traveling inside a wooden blocks.

means final velocity = u -25 % of u = u - u/4 = 3u/4

Now, use formula,

v² = u² + 2aS

Here, v = 3u/4, S = 14cm

∴ (3u/4)² = u² + 2a(14)

⇒9u²/16 - u² = 28a

⇒ - 7u²/16 = -28a

⇒ a = -u²/64

Let total distance covered by bullet before stopping is x = 14 + P

where P is distance covered by bullet after covering 14cm.

Now, use formula, v² = u² + 2as

here, v = 0, a = -u²/64

∴ 0 = u² - 2(u²/64)x

x = 32 cm

So, P = 32 - 14 = 18cm

Hence, bullet further travel 18cm before stopping.

Answer 2

»Here Let the Intial velocity of Bullet be v m/s

after traveling 14 cm the velocity becomes 75v/100 = 3v/4

Then by work-energy theorem,  W = (1/2)m{ v² - 9v²/16 }=> F×s = (1/2)m{ 7v²/16}=> F×(14/100)= 7mv²/32=> F = 25mv²/16

Distance travelled by the bullet before it stops=> F × s = mv²/2

=> 25mv²/(16) × s = mv²/2=> s = 8/25 m = 32 cms

So the distance traveled by bullet before stopping is 32 cms

So the distance bullet has to further travel after 14 cms to stop is 18 cms.