Question

calculate the kinetic energy of a 20kg mass moving at a speed of 4m/ s.​

Answer 1

Answer:

As there is no external non-conservative force on the system (both masses altogether) the linear momentum should

be conserved.

Thus we should have m

1

v

1

+m

2

v

2

=(m

1

+m

2

)V (inelastic collision)

V is the common velocity after the collision.

putting values we get 20(10)+5(0)=(20+5)V or V=8m/s

so the new KE will be K=

2

1

mV

2

=0.5×25×64=800Joule

Answer 2

Given:

• Mass (m) = 20 kg
• Velocity (v) = 4m/s

To Find:

• Kinetic energy

Formula Used:

• Kinetic energy = ½ × Mass × (velocity)²

Solution:

According to the Formula,

After putting the values;

➣ E.k = ½ × 20 × (4)²

➣ E.k = ½ × 20 × 4 × 4

➣ E.k = 160 J

Hence,

The Kinetic energy is 160 joules.

Remarks:

• E.k = Kinetic energy
• M = Mass
• SI unit of Kinetic energy is Joules.