02/06 Mechanics and Further Mechanics

Question 1

define weight

Answer 1

the force due to gravity pulling two objects together, N

Question 2

what is g

Answer 2

the acceleration due to gravity

Question 3

define normal contact force

Answer 3

a force perpendicular to a surface when two objects are in physical contact

Question 4

define Tension

Answer 4

a force which can be due to compression or stretching of a material
it always comes in pairs.

Question 5

how does Tension work due to stretching

Answer 5

the materials molecules are pulled apart and an attractive electromagnetic force between the molecules pulls them back together.

Question 6

how does Tension work due to compression

Answer 6

the material molecules are pushed together and a net repulsive electromagnetic force tries to push them further apart.

Question 7

define Friction

Answer 7

a force that acts against motion between two surfaces in contact

parallel to motion in the opposite direction.

Question 8

What does the size of a frictional force depend on?

Answer 8

• type of surface
• how hard the surfaces are pressed together.

Question 9

define the moment force

Answer 9

turning effect on an object. It is the product of the distance perpendicular to the force and the force applied.

Question 10

moment of a force about a point (Nm) =

Answer 10

force (N) x perpendicular distance from the force (m)

Question 11

what is a couple

Answer 11

two forces that are equal and opposite do not act along the same line meaning there is no resultant force but still a turning effect.

Question 12

what is the principal of moments

Answer 12

when an object is in equilibrium the sum of clockwise moments about any point equals the sum of anticlockwise moments about the same point.

Question 13

what is the centre of gravity

Answer 13

the point at which we can take its entire weight to act
THERE IS NO MOMENT DUE TO WEIGHT.

Question 14

what is the centre of mass

Answer 14

the point at which we can take the entire mass to be concentrated.

Question 15

what is a Stable object

Answer 15

the centre of mass and line of action lies between the object’s base/supports.

Question 16

Define mass

Answer 16

the amount of matter something contains, kg

Question 17

define Distance

Answer 17

how much ground an object has covered during its motion (scalar quantity).

Question 18

define Displacement

Answer 18

how far out of place an object is and the overall change in the object’s position (vector quantity).

Question 19

define speed

Answer 19

rate of change of distance.

Question 20

define velocity

Answer 20

rate of change of displacement.

Question 21

define Acceleration

Answer 21

rate of change of velocity.

Question 22

what do straight lines on a displacement time graph represent

Answer 22

constant velocity (if flat the velocity = 0).

Question 23

how to work out the instantaneous velocity from a dt graph

Answer 23

draw a tangent and find the gradient.

Question 24

how to work out the distance of journey from a dt graph

Answer 24

the sum of the slope heights including the negative (i.e. the max displacement is the distance travelled unless it started at a negative distance away that’s added to the max displacement away.)

Question 25

displacement of journey from a dt graph

Answer 25

sum of slope heights including negatives.

Question 26

how to get the max acceleration from a dt graph

Answer 26

find the initial and final velocity at two points by finding the gradient; divide by the time between the two points to get acceleration.

Question 27

what is the gradient of a vt graph

Answer 27

acceleration.

Question 28

what is the area under a vt graph

Answer 28

distance/displacement depending on negatives.

Question 29

when can suvat equations be used?

Answer 29

when an object moves with constant uniform acceleration.

Question 30

Suvat equation: X = X + XX

Answer 30

v = u + at.

Question 31

Suvat equation: X^n = X^n + nXX

Answer 31

v^2 = u^2 + 2as.

Question 32

Suvat equation: X = XX - nXX^n

Answer 32

s = ut - 1/2at^2.

Question 33

Suvat equation: X = n(X +X)X

Answer 33

s = 1/2(u + v)t.

Question 34

what is free fall

Answer 34

the only force acting on an object is gravity. Accelerate downwards at the same rate.

Question 35

what is the definition of terminal velocity

Answer 35

the highest attainable velocity of an object as it falls through a fluid; the drag = weight. terminal velocity can be different speeds i.e. a skydiver will have two different terminal velocities depending on if the parachute is open.

Question 36

projectile motion

Answer 36

an object follows a parabolic path.

Question 37

approaching a projectile's question

Answer 37

resolve the initial velocity into horizontal and vertical components; acceleration only acts on the vertical component and is g. horizontal distance can be easily calculated using the equation s = vt

Question 38

define Momentum

Answer 38

a vector quantity that is the product of the mass and velocity of an object.

Question 39

momentum, p (kgm/s) =

Answer 39

mass(kg) x velocity(m/s).

Question 40

definition of impulse

Answer 40

the increase/decrease in momentum.

Question 41

change in momentum =

Answer 41

Force x time.

Question 42

what is the area under a force time curve

Answer 42

the total impulse acting and the total change in momentum produced.

Question 43

what is the principal of conservation of momentum

Answer 43

in a closed system, the total momentum is constant so the momentum before a collision is equal to the momentum afterwards.

Question 44

define recoil

Answer 44

the movement backwards due to conserved momentum.

Question 45

define work done

Answer 45

the energy transferred whenever a force moves an object over a distance; scalar quantity measured in joules.

Question 46

work done, w (J) =

Answer 46

force, F (N) * displacement in the direction of the force, s (m).

Question 47

if the force and displacement are not in the same direction when calculating work done:

Answer 47

resolve the force; W = Fcosx * s.

Question 48

define energy

Answer 48

the ability to do work.

Question 49

what is the definition of 1 joule

Answer 49

the work done when a force of 1N moves through a distance of 1m in the direction of the force.

Question 50

define power

Answer 50

rate of doing work.

Question 51

power, P (W) =

Answer 51

= work done, w(J) / time taken, t (s) = force, F (N) * velocity, v (m/s).

Question 52

define Kinetic energy

Answer 52

the energy an object has because of its motion.

Question 53

K.E (J) =

Answer 53

1/2 * m* v^2.

Question 54

define Potential energy

Answer 54

the energy stored in an object due to its position, state or shape; e.g. gravitational, chemical, elastic, electrical or nuclear.

Question 55

GPE =

Answer 55

mgh.

Question 56

Elastic potential energy =

Answer 56

= 1/2Fx = 1/2 kx^2.

Question 57

define constant velocity

Answer 57

no resultant force and no work is done.

Question 58

what is the principle of conservation of energy

Answer 58

energy can be transferred from one form to another, but it cannot be created or destroyed. The total amount of energy always remains the same.

Question 59

define efficiency

Answer 59

the proportion of energy that is usefully transferred is called the efficiency of the machine.

Question 60

efficiency =

Answer 60

useful out/total in.

Question 61

linking k.e. and momentum K.E. =

Answer 61

p^2 / 2m.

Question 62

define statics

Answer 62

objects in equilibrium.

Question 63

define dynamics

Answer 63

objects that are accelerating/decelerating.

Question 64

The resultant vector must be drawn where…

Answer 64

the bases of the other two vectors meet.

Question 65

Why is calculated momentum not always correct?

Answer 65

At high speeds mass increases and the equations are only valid for non-relativistic speeds.

Question 66

what is an elastic collision

Answer 66

100% of energy and momentum conserved.

Question 67

define impulse

Answer 67

the change in momentum in a given time interval

Question 68

what is newtons first law

Answer 68

an object will continue to move with uniform velocity unless acted upon by a resultant external force.

Question 69

what is newtons second law

Answer 69

the rate of change of momentum of an object is directly proportional to the resultant force acting on it and will act in the same direction as that force.

Question 70

what is newtons third law

Answer 70

If object A exerts a force on object B then object B exerts an equal and opposite force back on A.

Question 71

conditions for a newtons third law pair

Answer 71

• forces must have the same magnitude • forces act along the same line but in opposite directions • forces act for/at the same time • forces act on a different object • forces are the same type.

Question 72

define an inelastic collision

Answer 72

momentum is conserved , some energy is lost to the surroundings (dissipated)