Question

27.
At a place where the acceleration due to gravity is
10m sec -2 a force of 5 kg-wt acts on a body of mass 10 kg
initially at rest. The velocity of the body after 4 second is
(EAMCET 1981)
(a) 5m sec-1
(b) 10m sec-1
(c) 20 m sec-1
(d) 50 m sec -1
​

Answer 1

this question is wrong as force= mass × acceleration and here 5=10×10 which is not possible

Answer 2

Given :-

• Acceleration (a) = 10 m/s²
• Force (f) = 5kg wt
• Mass (m) = 10 kg
• Initial Velocity (u) = 0 [Body was initially at rest]
• Time (t) = 4 sec

To Find :-

• Velocity of the body after 4 second = ?

Concept Implemented :-

✰ Equations of Motion

❶ First Equation of Motion

v = u + at

❷ Second Equation of Motion

s = ut + at²

❸ Third Equation of Motion

v² = 2as + u²

✰ Force = Mass × Acceleration

✰ F = ma

✰ 1 kg-Weight = 9.8 N

✰ 1 kg-Weight ≈ 10 N

Solution :-

◆ Let's first change the force from kg wt to N.

⌦ 1 kg wt = 10 N

⇒ 5 kg wt = 5 × 10 N

⇒ 5 kg wt = 50 N

∴ Force = 50 N

⌦ Force = Mass × Acceleration

⇒ 50 N = 10kg × Acceleration

⇒ 50/10 = Acceleration

⇒ 5 m/s² = Acceleration

⇒ Acceleration = 5 m/s²

∴ Acceleration = 5 m/s²

◆ Now we use First Equation of Motion

⌦ v = u + at

⇒ v = 0 + (5 × 4)

⇒ v = 0 + 20

⇒ v = 20 m/s

∴ v = 20 m/s

∴ The velocity of the ball after 4 seconds is 20 m/s.

Hence Option 【C】is correct. ✅

Learn More from Brainly :-

A stone thrown from the top of a building is given an initial velocity of m/s straight upward determine the time in second at which the stone reaches its maximum height. (Take g = 9.8 m/s²)

See answer at:

https://brainly.in/question/33630388