Terminal velocity implies constant kinetic energy and linearly decreasing potential energy

Steps:

• At constant speed, net force is zero, so acceleration is zero and velocity remains constant.
• Kinetic energy Ek = (1/2)mv² stays constant since velocity v is constant.
• Gravitational potential energy Ep = mgh decreases as height h decreases linearly with time at constant speed.
• Thus, graphs show Ek as a horizontal line and Ep as a straight line with negative slope.

Why B is correct:

• B depicts Ek constant (horizontal) and Ep decreasing linearly, matching Ep = mgh where h reduces at constant rate.

Why the others are wrong:

• A: Shows Ek increasing, implying acceleration, not constant speed.
• C: Shows both energies decreasing, ignoring constant Ek at terminal velocity.
• D: Shows Ep constant, contradicting ongoing descent.

Final answer: B