Question

A man drops a 20 kg object from the top of
a 10 m high building. What will be the
velocity of the object when it just hits the
ground?​

Answer 1

$\purple{\bold{\large\underline{\underline{Given\::-}}}}$

• Mass of object = 20kg
• Height of building = 10m

$\purple{\bold{\large\underline{\underline{To \: find:-}}}}$

• Velocity of object

$\purple{\bold{\large\underline{\underline{Formulas \: used:-}}}}$

• P.E. = mgh
• K.E. = 1/2 mv²

where,

• P.E. = Potential energy
• K.E. = Kinetic energy
• v² = (velocity)²
• m = mass

$\purple{\bold{\large\underline{\underline{Some \: common \: terms:-}}}}$

• The energy possessed by a body at rest in its changed position or change in size and shape is called the potential energy.
• The energy possessed by a body due to its state of motion is called the kinetic energy.

$\purple{\bold{\large\underline{\underline{Step \: by \: step \: explaination:-}}}}$

☯ Using the given formula of potential energy calculating the potential energy.

P.E. = mgh

Evaluating values in the given formula...

→ P.E. = 20×9.8×10

→ P.E. = 200×9.8

→ P.E. = 1960J

☯ As we came to knew the used potential energy so, it is converted into Kinetic energy inorder to calculate velocity.

☯ Using the formula of Kinetic energy...

K.E. = 1/2 mv²

Evaluating values in the given formula...

→ Kinetic Energy = 1/2 mass×velocity²

→ Kinetic Energy = 1/2 × 20 × v²

→ Velocity² = 3920/20

→ Velocity² = 196

→ Velocity = √196

→ Velocity = 14m/s

$\purple{\bold{\large\underline{\underline{Answer\::-}}}}$

Velocity would be 14m/s

$\purple{\bold{\large\underline{\underline{Extra \: information\::-}}}}$

•The kinetic energy possessed by a moving body is equal to the amount of work which the moving body can do before coming to rest.

• Kinetic energy depends upon square of its velocity of motion.

• A faster moving body has more kinetic energy than a slowly moving body.

• The potential energy of a body at a height is measured above the ground is measured by the amount of work done in lifting it up from the ground.

• The potential energy is denoted by the symbol U.

• The Kinetic energy is denoted by the symbol K.