Dynamics

Question 1

Resultant force formula,

in words

in symbols

Answer 1

resultant force = mass x acceleration

F = ma

Question 2

Newton’s second law definition

Answer 2

resultant force is proportional to mass multiplied by acceleration

or

resultant force is proportional to rate change of momentum

Question 3

Inertia definition

Answer 3

a measure of how difficult it is to change the velocity of an object or to change its speed or direction, a measure of the mass of an object (a massive object has large inertia)

Question 4

Weight definition

Answer 4

the force on an object caused by a gravitational field acting on its mass

Question 5

Friction

Answer 5

the name for a resistive force when two surfaces are in contact and tending to slide over one another

Question 6

Types of forces x6

Answer 6

pushes and pulls - force of car engine

weight - force of gravity

drag - air resistance

upthrust - in fluids

normal force - contact force

tension - pulling with a rope or compressing a spring

Question 7

Centre of gravity definition

Answer 7

the point on a body where the entire weight of the body is considered to act

Question 8

Weight formula,

in words

in symbols

Answer 8

weight = mass x acceleration of free fall

W = mg

Question 9

Acceleration of free fall on the moon

Answer 9

1.6ms^-2

Question 10

Uniform motion definition

Answer 10

the natural state of motion of an object of uniform velocity, constant speed and direction

Question 11

Newton’s first law of motion definition

Answer 11

an object will remain at rest or in a state of uniform motion unless it is acted upon by a resultant force

Question 12

Resultant force definition

Answer 12

the single force that has the same effect as all of the forces acting on an object

Question 13

Terminal velocity definition

Answer 13

the maximum velocity reached by an object falling under gravity or accelerated by a constant force

Question 14

Velocity-time graph of parachute fall

Answer 14

Negative parabola from origin of graph while jumping

Steep negative gradient after parachute is opened

Smooths into no gradient when jumper begins to fall again

Question 15

Resistive force definition

Answer 15

a backwards force in the opposite direction to movement caused by friction or some viscous force

Question 16

Drag definition

Answer 16

a force that resists the movement of a body through a fluid

Question 17

Contact force definition

Answer 17

the force at right angles to a surface when 2 objects are in contact

Question 18

Upthrust definition

Answer 18

the force upwards in a liquid or gas caused by the pressure in the gas or liquid

Question 19

Newton’s third law of motion definition

Answer 19

when 2 bodies interact, the forces they exert on each other are equal in size and opposite in direction

Question 20

Understanding SI units in terms of physical quantities

Answer 20

All physical quantities have a numerical magnitude and a unit

Question 21

Base unit definition

Answer 21

defined units of the SI system from which all other units are derived

Question 22

Derived units definition

Answer 22

units that are the combinations of the base units of the SI system

Question 23

Newton definition

Answer 23

one newton is the force that will give a 1kg mass an acceleration of 1ms^-2 in the direction of the force

Question 24

Base units in mechanics x5

Answer 24

length (m)
mass (g)
time (s)
current (I)
temperature (K)