2-forces and motions Flashcards

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1
Q

whats the distance time graph for a stationary object

A

horizontal line

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2
Q

whats the distance time graph for an object at constant speed

A

straight line with a positive slope

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3
Q

what does the distance time graph gradient represent

A

speed

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4
Q

whats the formula for speec

A

speed = distance traveled/time taken

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5
Q

what typa quantity is speed

A

a scalar quantity,magnitude but no direction

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6
Q

what type od quantity is distance

A

scaler

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6
Q

what is displacement

A

ditance in a given direction. its a vector quantity

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7
Q

what is velocity

A

speed in a given direction

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8
Q

why is velocity a vector quantity

A

because it has both a magnitude and direction

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9
Q

whats the formula for velocity

A

velocity=displacement/time

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10
Q

whats tehe formula for acceleration

A

change in velocity/time

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11
Q

how can u find distance from a velocity time graph

A

the area under a velocity time graph

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12
Q

what does it mean of the velocity time graph has a horizontal gradient

A

constant acceleration

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13
Q

what happens if 2 objects push eachother apart

A

if they have diff mass they will move with diff speeds
if they have the same mass there will be equal and opposite momentum

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14
Q

what is meant by deceleration

A

negative acceleration

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15
Q

what is the formula for momentum

A

mass x velocity

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16
Q

whats the unit for momentum

A

kg/m/s

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17
Q

what happens if resultant force exerted on an object increases

A

total acceleration increases

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18
Q

what is newtons second law

A

force(n) is equal to mass (g) times acceleration

19
Q

how do you find the gradient by drawing a tangent on a graph

A

height/base

20
Q

descrube newtons 2nd law

A

f=ma so objects acceleration is the same direction as the resultant force on the object, force must be accting on object to cause or change an acceleration.

21
Q

why is driving velocity constant

A

driving force is equal to resistant force (ex friction or air)

22
Q

what is stopping distance and what is it made of

A

shortest diistance taken for a vehicle to stop
thinking distance(distance traveled during drivers reaction time) + breaking distance(distance traveled by car during breaking)

23
Q

whatre the factors that effect thinking distance

A

tiredness alcohok and drugs since driver may be distracted

24
Q

whatre the factors effecting stopping distance

A

higher speed,bad weather conditions and bad car maintenence will all lead to a longer stopping distance (car takes longer to stop)

25
Q

what happens when car decelerates

A

breaks overheat due to friction between breaks and wheels then kinetic energy os transfered into thermal energy

26
Q

whats newtons 1st law

A

if resultant force acting on a object is 0
-a moving object will continue to move at the same velocity
-a stationary object will remain at rest.

27
Q

what is newtons 3rd law

A

Whenever two objects interact, the forces they exert on each other are equal in magnitude and opposite in direction.

28
Q

what is resultant force

A

total force acting on an object. a single force that has the same effect on the motion as all the original forces acting together.

29
Q

what happens in terms of acceleration if the resultant force on an object is not zero

A

the object will accelerate in the direction of the resultant force.

30
Q

what is conservation of momentum

A

in a closed system the total momentum before an interaction is equal to the total momentum after the interaction.

31
Q

whats the relationship between force, F, change in momentum, ∆p, and time, t,

A

force = change in momentum/time

32
Q

what happens to objects moving fast through fluids

A

object experiences friction. The faster the object moves, the greater the
frictional forces (drag) acting on it.

33
Q

what happens to objects moving throught fluid in terms of acceleration

A
  • initially accelerate due to the force of gravity -> the drag forces increase as the velocity increases. -> the resultant force will be zero and the object will move at its terminal velocity.
34
Q

why are parachutes designed (in terms of terminal velocity)

A

to increase the drag force on a parachutist so that the terminal velocity is reduced.

35
Q

what does streamlinig do

A

reduces the drag force on an object so that its maximum velocity is increased.

36
Q

whats the center of mass

A

is the point at which the mass of the object may be thought to be
concentrated.

37
Q

how do you calculate moment

A

force times perpendicular distance

38
Q

whats the unir of moment

A

newton meters (Nm)

39
Q

where is the center of mass in a suspended object

A

directly beneath the point of suspension

40
Q

where is the center of mass in a symmetrical object

A

along the axis of symmetry

40
Q

whats the moment of a force

A

measure of turning effect on the force of an object

41
Q

what happens if an object is balanced

A

the total clockwise moment must be exactly balanced by the total anticlockwise
moment about any pivot.

41
Q

what happens if the line of action (center of mass) lies outside base of an object

A

there will be a resultant moment and the body will topple.

42
Q

how can stability of an object be increased

A

lowering the center of mass and increasing its base distance

43
Q

when do objects topple

A

if its point of turning isnt 0 and its line of action acts AWAY from the equilibrium (balanced base)

44
Q

how can simple levers be used

A

force transmitters, they transfer force from 1 side of pivot to another