Question

An object of mass 70 kg is raised to a height of 10 metre above the ground what is its p if the object is allowed to fall find its ke even it is halfway down

Answer 1

Given Parameters :

• Mass of the object = 70 kg
• Height of the object = 10 m
• Acceleration due to gravity = 9.8 m/s²

Unknown:

• Kinetic Energy = ?

Formulas :

• Potential Energy = mgh
• Third equation of motion = v² = u² + 2as
• Kinetic energy = ½ mv²

Answer:

Potential Energy at height 10 m :

→ Potential Energy = mgh

→ Potential Energy = 70 × 9.8 × 10

→ Potential Energy = 6860 J

Objects falls on halfway :

Here,

• Initial Velocity (u) = 0 m/s
• Distance (s) = 5 m (The object is halfway down)
• Acceleration due to gravity = 9.8 m/s²
• Final Velocity (v) = ?

Lets find (v) by Using third equation of motion :

➝ v² = u² + 2as

➝ v² = (0)² + 2(9.8)(5)

➝ v² = 98

➝ v = 9.89 m/s

Now, We can calculate Kinetic Energy

᠉ Kinetic Energy = ½ mv²

᠉ Kinetic Energy = ½ (70)(9.89)²

᠉ Kinetic Energy = ½ (70)(97.8121)

᠉ Kinetic Energy = ½ (6486.847)

᠉ Kinetic Energy = 3423.4235 J