Question

A truck of mass 5000 kg increases its speed from 36 km h-1 to 72 km h-1. Find
the increase in its kinetic energy.​

Answer 1

Answer:

• 7,50,000 J

Steps:

Mass of the truck = 5000 kg

Initial Speed = 36 km/hr

Final Speed = 72 km/hr

Converting Speed from km/hr to m/s,

Initial Speed = 36 * 5/18 = 10 m/s

Final Speed = 72 * 5/18 = 20 m/s

Formula for calculating initial Kinetic Energy,

K.E = 0.5 mv²

→ Initial K.E. = 0.5 × 5000 × (10)²

→ Initial K.E. = 2500 × 100 = 2,50,000 J

→ Final K.E. = 0.5 × 5000 × (20)²

→ Final K.E. = 2500 × 400

→ Final K.E. = 10,00,000 J

Hence Increase in K.E. is given as:

→ Final K.E. - Initial K.E.

→ 10,00,000 - 2,50,000 = 7,50,000 J

Hence the increase in Kinetic Energy is 7,50,000 J.

Answer 2

Answer:

Question:-

A truck of mass 5000 kg increases its speed from 36 km h-1 to 72 km h-1.

Explanation:

Given :-

• Mass of the truck= 5000 kg
• Initial speed of the body = 36 km/h
• Final speed of the body = 72 km/h

Find out

• The increase in it's kinetic energy

Convert

• Initial speed given : 36 km/h × 5/18 = 10m/s
• Final speed given: 72 km/ h × 5/18 = 20 m/s

Formula used for making

Out the Kinetic energy of

both initial and final kinetic

energy

K.E.= 0.5 mv²

Initial K.E. = 0.5 × 5000 × 10²

Initial K.E.= 2500 × 100 = 2,50,000 joule

Final K.E. = 0.5 × 5000 × 20²

Final K.E. = 2500 × 400

= 10,00,000 joule

•°•Increase in Kinetic energy is given as

By subtracting

= 》Final K.E.-Initial K.E.

=》 10,00,000 - 2,50,000

=》 7,50,000 joule

•°• The kinetic energy increases by 7,50,000 joule

Know more !

• Joule is the S.I. unit of all kind of energy
• James Prescott Joule FRS FRSE was an English physicist, mathematician and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work. This led to the law of conservation of energy, which in turn led to the development of the first law of thermodynamics. 
• Born: 24 December 1818, Salford, United Kingdom
• Died: 11 October 1889, Sale, United Kingdom