Question

1. A 1000 Kg car is moving with a velocity of 100 metre/sec. How fast should a 250 Kg
motorcycle move to have the same kinetic energy as the truck?
a. 400 metre/sec
b. 200 metre/sec
c. 100 metre/sec
d. None of the above
​

Answer 1

Answer:

• (b) 200 metre/sec is the required answer.

Explanation:

Given:-

• Mass of Car ,m = 1000 kg
• Velocity ,v = 100m/s
• Mass of Motorcycle ,m' = 250 kg
• Both have same Kinetic Energy

To Find:-

• Velocity of Motor cycle ,v'

Solution:-

Firstly we calculate the Kinetic Energy of the Car

Kinetic Energy is defined as the energy possess by body due to its motion.

• KE = 1/2mv²

Where,

• KE is the Kinetic Energy
• m is the mass
• v is the speed/velocity

Substitute the value

→ KE = 1/2×1000 × 100²

→ KE = 500 × 10000

→ KE = 5000000 J

• Hence, kinetic energy of car is 5000000 Joules.

Now, it is given that the motorcycle have also same kinetic energy.

• KE = 1/2m'v'²

Substitute the value we get

→ 5000000 = 1/2×250×v'²

→ 5000000 = 125 × v'²

→ v'² = 5000000/125

→ v'² = 40000

→ v' = √40000

→ v' = 200 m/s

• Hence, the velocity of the motorcycle is 200m/s.

Answer 2

Answer:

Given :-

• Mass of car = 1000 kg
• Velocity of car = 100 m/s
• Mass of motorcycle = 250 kg

To Find :-

Velocity of motorcycle

Solution :-

At first let's find Kinetic energy of car

KE = ½ × mv²

KE = ½ × 1000 × 100²

KE = 500 × 100 × 100

KE = 5000000 J

Now,

Finding velocity of motorcycle

5000000 = ½ × 250 × v²

5000000 × 2 = 250 × v²

10000000 = 250× v²

v² = 10000000/250

v² = √40,000

v = 200 m/s

Hence :-

Option B is correct