A force of 50N acts on a body of mass 8 kg at rest for 4 seconds.
a) What was the initial kinetic energy of the body?
b) What was the acceleration produced in the body?
c) What was the velocity of the body after 4 seconds?
d) What was the kinetic energy of a body after 4 seconds?
e) What was the distance moved by the body in four seconds?
Answers
Given that,
- Force = 50 N
- Mass = 8 kg
- Acceleration = ?
- Time = 4 seconds.
we know that,
⇒ Force = Mass × Acceleration
⇒ 50 N = 8 Kg × Acceleration [1N = 1 kg× m/s²]
⇒ Acceleration = 50×kg×m/s²/8 kg
⇒ Acceleration = 6.25 m/s²
∴ Acceleration is 6.25 m/s².
Velocity of the body after 4 seconds =
Given that,
- Initial velocity = 0 m/s² (u) [Because the body is at rest]
- Acceleration = 6.25 m/s² (a)
- Time = 4 seconds (t)
- Velocity of the body = ? (v)..
we know,
⇒ v = u + at
⇒ v = 0 m/s²+6.25 m/s²×4 sec
⇒ v = 0 m/s²+25 m/s²
⇒ v = 25 m/s².
∴ Velocity of the body after 4 seconds is 25 m/s².
Kinetic energy of the body =
Given that,
- Mass of the body = 8 kg (m)
- Velocity of the body = 25 m/s² (v)
- Kinetic Energy = ? (KE).
We know,
⇒ KE = 1/2mv²
⇒ KE = 1/2×8kg×(25)²
⇒ KE = 4kg × 225 m/s²
⇒ KE = 900 Joules.
∴ Kinetic Energy produced in the body is 900 Joules.
Distance travelled by the body in 4 seconds =
Given that,
- Acceleration = 6.25 m/s² (a)
- Initial velocity = 0m/s² (u) [∵ The body is at rest]
- Time = 4 sec (t)
- Distance travelled by the body = ? (s)
we know,
⇒ s = ut + 1/2at²
⇒ s = (o m/s²)(4 sec) + 1/2×6.25 m/s²×(4sec)²
⇒ s = 0 m/s + 1/2×6.25 m/s²×16 sec²
⇒ s = 0 m/s + 6.25 m/s²×8 sec²
⇒ s = 50 m
∴ The distance travelled by the body in 4 seconds is 50 m.
Initial kinetic energy of the body =
Mass = 8 kg (m)
Velocity = 0 m/s² (v)
Kinetic Energy = ? (KE)
we know,
KE = 1/2mv²
KE = 1/2×8 kg × (0 m/s)²
KE = 1/2×0
KE = 0 Joule.
∴ The initial Kinetic energy of the body is 0 Joule.
Hope these answers helps you.
Thank you for your question it had helped me to think.
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