Explanation

• The minimum number of forces required to use the head-to-tail rule for vector addition is two.
• In this method, the tail of the second force vector is placed at the head of the first force vector.
• The resultant force is drawn from the tail of the first vector to the head of the last vector.
• This rule can also be used to add three or more forces.

Last verified on 26-10-2026

Explanation

• Tactile means related to the sense of touch.
• Visible means able to be seen by the sense of sight.
• Both pairs connect a sensory-related word with the sense it is associated with.

Last verified on 26-10-2026

Explanation

Torque is the turning effect of a force around a pivot.

Distance = 10 cm = 0.1 m.

Torque = 100 × 0.1 = 10 Nm.

Last verified on 26-10-2026

Explanation

Potential energy depends on mass, gravitational acceleration, and height.

PE = 50 × 10 × 3 = 1,500 J.

Last verified on 26-10-2026

Explanation

• Mass = Weight ÷ g = 12,000 ÷ 10 = 1,200 kg.
• Kinetic energy = ½ × mass × velocity² = ½ × 1,200 × 20² = 240,000 J = 240 kJ.

Last verified on 26-10-2026

Explanation

• Petroleum, Coal, and Natural gas are all fossil fuels. 
• They are non-renewable energy sources 
• Major contributors to global energy production.
• Coal: A solid fossil fuel primarily derived from ancient swamp plants.
• Petroleum (Oil): from the remains of marine microorganisms like plankton.
• Natural gas: Composed of methane, often found in underground deposits alongside petroleum or coal

Last updated on 06-March-2026

Explanation

• A body is in neutral equilibrium when its centre of gravity remains at the same height after being displaced.
• The body stays in its new position because its potential energy does not change.
• Example: A ball rolling on a flat horizontal surface is in neutral equilibrium.

Additional information:

• In stable equilibrium, the centre of gravity rises when the body is displaced.
• In unstable equilibrium, it falls.

Last verified on 26-10-2026

Explanation

• Newton's law of gravitation explains the gravitational force between Earth and an object.
• The gravitational force is given by F = GMm / R^2, where M is Earth's mass, m is the object's mass, and R is Earth's radius.
• By equating gravitational force with the object's weight, F = mg, Earth's mass can be calculated using M = gR^2 / G.
• The approximate mass of Earth is 5.97 x 10^24 kg.

Last verified on 26-10-2026

Explanation

• A force in a three-dimensional Cartesian coordinate system has three perpendicular components: X, Y, and Z.
• These components act along three mutually perpendicular axes.

Additional information:

• In a two-dimensional coordinate system, a force has only two perpendicular components: X and Y.

Last verified on 26-10-2026

Explanation

Given:

F = 200 N

m = 20 kg

u = 0 m/s (from rest)

v = 50 m/s

Formula: Work done = Change in Kinetic Energy

F _ s = 1/2 _ m _ v^2

200 _ s = 1/2 _ 20 _ 50 _ 50

200 _ s = 10 _ 2500

200 _ s = 25000

s = 25000 / 200

s = 125 m

Last verified on 26-10-2026