Conservation of Mechanical Energy

Steps:

• The ball is dropped with no air resistance, so mechanical energy (KE + PE) is conserved.
• At point 1 (top), potential energy is maximum, kinetic energy is zero.
• As it falls to points 2 and 3, potential energy decreases while kinetic energy increases by the same amount.
• Total energy remains constant throughout the motion.

Why A is correct:

• The law of conservation of energy states that in the absence of non-conservative forces like air resistance, total mechanical energy is constant.

Why the others are wrong:

• B: Total energy equals maximum PE at point 1 but is the same everywhere, not greatest.
• C: At point 2, PE is less but KE is more, so total energy is unchanged.
• D: At point 3 (bottom), PE is minimum but KE is maximum, so total energy is still the same.

Final answer: A