Question

a brick of mass 0.8 kg is accidentally dropped from a high scaffolding. it reaches the ground with a kinetic energy of 240 J. How high is scaffolding ?(Take acceleration due to gravity g be 10 m s-¹)​

Answer 1

30 m

General Formulas and Concepts:

Energy

Gravitational Potential Energy:
`\displaystyle U_g = mgh`

• m is mass (in kg)
• g is gravity
• h is height (in m)

Kinetic Energy:
`\displaystyle KE = (1)/(2)mv^2`

• m is mass (in kg)
• v is velocity (in m/s²)

Law of Conservation of Energy

Step-by-step explanation:

Step 1: Define

Identify variables

[Given] m = 0.8 kg

[Given] g = 10 m/s²

[Given] U = 240 J

[Solve] h

Step 2: Solve for h

1. [LCE] Substitute in variables [Gravitational Potential Energy]: (0.8 kg)(10 m/s²)h = 240 J
2. Multiply: (8 kg · m/s²)h = 240 J
3. Isolate h [Cancel out units]: h = 30 m