(i) Since, space station and astronauts have equal acceleration, they are under free fall condition.
(ii) Both the astronauts and the space station are in the state of weightlessness.
(iii) They are not actually floating but falling freely around the earth due to the huge orbital velocity.

(i) Catching a cricket ball the fielder lowers his hands backwards. Because, he stops his hands soon after catching the ball, the ball comes to rest very quickly.
(ii) It means that the momentum of the ball is brought to rest very quickly.
(iii) So the average force acting on the body will be large.
(iv) Due to this large average force, the hands will get hurt.
(v) To avoid getting hurt, the player brings the ball to rest slowly.

(i) A spanner has a long handle to produce a larger moment of force by a small force applied normally at the end of its handle.
(ii) Moment of force = \(\overrightarrow{\mathbf{F}} \times \overrightarrow{\mathrm{d}}\)

(i) "According to Newton's second law, the force acting on a body is directly proportional to the rate of change of linear momentum of the body and the change in momentum takes place in the direction of the force".
(ii) Force = mass x acceleration
(iii) F = m x a

(i) When a number of like or unlike parallel forces act on a rigid body and the body is in equilibrium, then the algebraic sum of the moments in the clockwise direction is equal to the algebraic sum of the moments in the anti-clockwise direction.
(ii) Moment in clockwise direction = Moment in anticlockwise direction.
(iii) F₁ x d₁ = F₂ x d₂.

(i) The rotating effect of a couple is known as moment of a couple.
(ii) Eg: Turning a tap, winding or unwinding a screw, spinning of a top, etc...
(iii) Moment of a couple = Force x perpendicular distance between the line of action of force.
(iv) M = F x S

Let, F₁ = 5 N
F₂ = 15 N
F_net = F₂ - F₁            [∵ F₂ > F₁]
= 15 - 5 = 10 N
F_net i.e, the resultant force acts along the direction of the greater force 15 N.

Based on the direction in which the force acts, they can be classified into two types as:
(i) Like Parallel forces
(ii) Unlike Parallel forces.

The inherent property of a body to resist any change in its state of rest or the state of uniform motion, unless it is influenced upon by an external unbalanced force is known as 'inertia'.
Types:
(i) Inertia of rest
(ii) Inertia of motion
(iii) Inertia of direction