05 Vectors, Moments And Projectiles Flashcards

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1
Q

What is the effect a force has in a particular direction called?

A

The component of the force in that direction.

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2
Q

How do you resolve a a component of a force?

A

By drawing a component triangle

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3
Q

Does a force acting vertically have a horizontal component?

A

No

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4
Q

Does a force acting horizontally have a vertical component?

A

No

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5
Q

In vector diagrams where do arrows start?

A

At the head of the previous one

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6
Q

What is the overall effect of a combination of two or more forces called?

A

The resultant force

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7
Q

How is the resultant shown in a vector diagram?

A

A line drawn from the start to finish.

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8
Q

On a question on vector diagrams, when it askes for the direction what does that mean?

A

Find the angle

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9
Q

Why is a closed triangle of vectors a closed triangle?

A

Because there is no resultant force and it is in equilibrium.

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10
Q

What is the centre of mass?

A

The point through which a single force on the body does not cause the body to turn. (The point were all the objects weight appears to act.)

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11
Q

When vectors aren’t perpendicular, how do you find the resultant …etc?

A

Draw a scale diagram.

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12
Q

What can cause turning effects?

A

Forces

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13
Q

What is the definition of the moment of a force about a point?

A

Force multiplied by the perpendicular distance from the point to the line of action of the force.

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14
Q

What is the principle of moments?

A

For an object to be in equilibrium, the sum of the clockwise moments about a point is equal to the sum of the anticlockwise moments about the same point.

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15
Q

A system is in equilibrium if…

A

•there is no resultant force acting on it AND
•there is no resultant moments acting on it

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16
Q

What is moments measure in?

A

Nm

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17
Q

What is tension the same as?

A

Force

18
Q

Define a couple.

A

A pair of equal and opposite parallel forces acting on a body, but not along the same line, causing the body to turn about a pivot.

19
Q

Define a moments of a couple.

A

One force x the perpendicular distance between the lines of action of the 2 forces.

20
Q

What is a moment of a couple also known as?

A

A torque

21
Q

When an object is in equilibrium, what is the sum of the upwards force equal to?

A

The sum of the downwards force.

22
Q

When in equilibrium, what is the clockwise moment (CWM) equal to?

A

The anticlockwise moment (ACWM) [CWM=ACWM]

23
Q

In suvat equations, is the ‘s’ vertical or horizontal?

A

Vertical

24
Q

In the equation s=s/t, is the ‘s’ vertical or horizontal?

A

Horizontal

25
Q

What is the definition of a projectile?

A

A moving object on which the only force acting on it is weight.

26
Q

During projectiles, what is the acceleration due to gravity?

A

9.81 m s‐²

27
Q

If a ball is thrown upwards what is its acceleration?

A

-9.81

28
Q

If a ball is dropped downwards, what is the acceleration?

A

9.81

29
Q

If one object is projected horizontally and another identical object is allowed to fall vertically, what can be concluded about their acceleration?

A

They have the same vertical acceleration.

30
Q

If one object is projected horizontally and another identical object is allowed to fall vertically, which will hit the floor first?

A

They will reach the floor at the same time.

31
Q

When finding a vertical projection, what equation should you always use?

A

V=s/t

32
Q

When calculating vertical projection, what type of equation should you always use?

A

SUVAT equations.

33
Q

What is the vertical component of velocity independent to?

A

Horizontal component of velocity

34
Q

What does an object projected sideways follow?

A

A parabolic path.

35
Q

When do vertical arrows during projection get longer?

A

As the object gets closer to the ground.

36
Q

During a horizontal projection, why are the horizontal arrows always the same length?

A

Because the horizontal velocity is constant.

37
Q

If 1 ball is projected and another is in free fall, which ball will hit the ground first?

A

Both at the same time.

38
Q

Explain the monkey and the hunter?

A

A hunter is about to shoot a monkey hanging from a branch so the monkey decides to drop of the branch when the bullet is shot. The monkey falls vertically with an acceleration of 9.81m s‐². The bullet also falls vertically at an acceleration of 9.81m s‐² following a parabolic path. Therefore the bullet will still hit the monkey.

39
Q

When firing an object at an angle, when is the horizontal velocity constant?

A

Always

40
Q

When firing an object at an angle and you have that velocity, how do you find the horizontal or vertical velocity?

A

Trigonometry.