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Tension is a force exerted by a cord, rope, or similar object under pulling stress. In the context of pulleys, the tension in the cord is crucial to analyze. When lifting a canister at a constant speed using pulleys, tension is balanced by the force of gravity. For instance, the gravitational force on a 20 kg canister is determined by \(F_g = 196 \text{ N}\). When the cord loops around a pulley, the net force is twice the tension, implying \(2T = 196 \text{ N}\). Solving for tension, we get \(T = 98 \text{ N}\). This tension must be maintained by the force you exert. So, the force \(F\) needed to lift the canister at a constant speed is precisely equal to the tension in the cord, \(F = 98 \text{ N}\).
Understanding tension helps explain why certain forces are required to maintain equilibrium in pulley systems and similar setups.

Work and energy principles are vital for understanding how forces cause displacement and how energy is transferred. Work is calculated with the formula \(W = F \times d\). Here, \(F\) is the force applied (98 N) and \(d\) is the displacement (0.04 m). Thus, work done by your force in raising the canister by 2.0 cm is \[W = 98 \text{ N} \times 0.04 \text{ m} = 3.92 \text{ J}\].
This shows energy is transferred from you to the canister, elevating it against gravity. The work-energy theorem states that the work done on an object results in a change in its energy. In this case, your applied work exactly counteracts the gravitational potential energy change, ensuring a smooth and constant lift.

Gravitational force is the attractive force between two masses. It plays a significant role in the example of lifting a canister. The force due to gravity on the canister is \(F_g = mg\), calculated as \((20 \text{ kg} \times 9.8 \text{ m/s}^2 = 196 \text{ N})\).
This force resists your pulling effort. When raising the canister by 2.0 cm (0.02 m), the gravitational force acts downward. The work done by gravity is therefore: \[W = F_g \times h = 196 \text{ N} \times 0.02 \text{ m} = 3.92 \text{ J}\].
Since gravity acts in the opposite direction of motion, the work done by the gravitational force is negative. Essentially, you're doing positive work to lift the canister, while gravity does negative work, maintaining energy balance. This illustrates how understanding gravitational force is essential for predicting and calculating work and energy in physical systems.