Acceleration is defined as the rate of change of velocity. If velocity remains constant, the rate of change is zero.

Newton's First Law states that an object will remain at rest or in uniform motion unless acted upon by an external force, which is the definition of inertia.

The Newton (N) is the SI unit of force, defined as 1 kg·m/s².

Newton's Third Law states that for every action, there is an equal and opposite reaction.

Inertia is the inherent property of matter that resists changes to its current state of motion.

Centripetal force is a net force that acts on an object to keep it moving along a curved path.

Velocity has both magnitude and direction, making it a vector quantity, whereas speed is a scalar.

In a velocity-time graph, the gradient or slope represents the rate of change of velocity, which is acceleration.

According to F=ma, a = F/m. If m is doubled, 'a' becomes inversely proportional, thus it is halved.

When an elevator accelerates upward, the normal force exerted by the floor on the person increases to provide both the weight of the person and the additional upward acceleration, resulting in greater apparent weight.

Momentum (p) is defined as the product of the mass of an object (m) and its velocity (v), represented as p=mv.

Using the kinematic equation v = u + gt, where u = 0, v = 10 m/s² * 3 s = 30 m/s.

Impulse is the product of force and time, so its SI unit is Newton-second (N·s), which is equivalent to kg·m/s.

In a vacuum, there is no air resistance. Acceleration due to gravity is independent of mass; thus, all objects fall with the same constant acceleration (g).

Limiting friction is the maximum value of static friction that occurs when an object is on the verge of sliding.

Joule is energy, Watt-hour is power times time (energy), and Newton-meter is work (energy). Newton-second is the unit of impulse or momentum, not energy.

When a cyclist turns on a flat road, the necessary centripetal force for circular motion is provided by the static frictional force between the tires and the ground.

According to the impulse-momentum theorem, the change in momentum (impulse) is equal to the product of force and the time interval during which it acts.

The time to reach maximum height is half the total time, i.e., 2 seconds. Using s = ut + 0.5at² (or v² = u² + 2as), with initial velocity u = 20 m/s, height s = 20*2 - 0.5*10*4 = 20m.