Newton's Laws and Application of Newton's Laws

Question 1

Kinetic Frictional Force

Answer 1

Kinetic Frictional Force (fk) is the force that opposes the motion of a moving object relative to a surface.

Question 2

Newton’s Second Law of Motion

Answer 2

Newton’s Second Law of Motion states when a resultant/net force acts on an object, the object will accelerate in the direction of the force at an acceleration directly proportional to the force and inversely proportional to the mass of the object.

Question 3

Newton’s Law of Universal Gravitation

Answer 3

Newton’s Law of Universal Gravitation states that each body in the universe attracts every other body with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.

Question 4

Newton’s First Law of Motion

Answer 4

Newton’s First Law of Motion states that a body will remain in its state of rest or motion at constant velocity unless a non-zero resultant/net force acts on it.

Question 5

Normal Force

Answer 5

Normal Force N, as the force or the component of a force which a surface exerts on an object with which it is in contact, and which is perpendicular to the surface.

Question 6

Newton’s Third Law of Motion

Answer 6

Newton’s Tird Law of Motion states that when one body exerts a force on a second body, the second body exerts a force of equal magnitude in the opposite direction on the first body.

Question 7

Acceleration

Answer 7

Acceleration is the rate of change in velocity (vector).
a=△v/△t

Question 8

Resultant Vector (Force)

Answer 8

A Resultant Vector (Force) is the vector (force) sum of two or more vectors (forces), i.e. a the single vector (force) having the same effect as two or more vectors (forces)
together.

Question 9

Vector

Answer 9

A vector is a physical quantity with magnitude and direction.

Question 10

Scalar

Answer 10

A scalar is a physical quantity with magnitude only.

Question 11

One-dimensional motion

Answer 11

One-dimensional motion is motion along a straight line. The object may move forward or backward along this line.

Question 12

Distance

Answer 12

Distance is the total path length travelled (scalar).

Question 13

Displacement

Answer 13

Displacement is the difference in position in space (vector).

Question 14

Average Speed

Answer 14

Average Speed is the total distance travelled per total time (scalar).

Question 15

Average Velocity

Answer 15

Average Velocity is the rate of change of position (vector).
v=△x/△t

Question 16

Instantaneous Velocity

Answer 16

Instantaneous Velocity is the rate of change of position, i.e. the displacement divided by a very small time interval or the velocity at a particular time (vector).

Question 17

Instantaneous Speed

Answer 17

Instantaneous Speed is the magnitude of the instantaneous velocity (scalar).

Question 18

Frictional Force

Answer 18

Frictional Force (f) is the force that opposes the motion of an object and which acts parallel to the surface.

Question 19

Static Frictional Force

Answer 19

Static Frictional Force (fs) is the force that opposes the tendency of motion of a stationary object relative to a surface.

Question 20

Describe Weight

Answer 20

Describe weight as the gravitational force, in newton (N), exerted by the Earth on an object. Describe mass as the amount of matter in a body measured in kilogram (kg).
w=mg

Question 21

Explain Weightlessness

Answer 21

Explain weightlessness as the sensation experienced when all contact forces are removed, i.e. no external objects touch one’s body. For example, when in free fall, the only force acting on your body is the force of gravity that is a non-contact force. Since the force of gravity cannot be felt without any other opposing forces, you would have no sensation of it and you would feel weightless when in free fall.