05 Vectors, Moments And Projectiles

Question 1

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

Answer 1

The component of the force in that direction.

Question 2

How do you resolve a a component of a force?

Answer 2

By drawing a component triangle

Question 3

Does a force acting vertically have a horizontal component?

Answer 3

No

Question 4

Does a force acting horizontally have a vertical component?

Answer 4

No

Question 5

In vector diagrams where do arrows start?

Answer 5

At the head of the previous one

Question 6

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

Answer 6

The resultant force

Question 7

How is the resultant shown in a vector diagram?

Answer 7

A line drawn from the start to finish.

Question 8

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

Answer 8

Find the angle

Question 9

Why is a closed triangle of vectors a closed triangle?

Answer 9

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

Question 10

What is the centre of mass?

Answer 10

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.)

Question 11

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

Answer 11

Draw a scale diagram.

Question 12

What can cause turning effects?

Answer 12

Forces

Question 13

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

Answer 13

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

Question 14

What is the principle of moments?

Answer 14

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.

Question 15

A system is in equilibrium if…

Answer 15

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

Question 16

What is moments measured in?

Answer 16

Nm

Question 17

What is tension the same as?

Answer 17

Force

Question 18

Define a couple.

Answer 18

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.

Question 19

Define a moments of a couple.

Answer 19

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

Question 20

What is a moment of a couple also known as?

Answer 20

A torque

Question 21

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

Answer 21

The sum of the downwards force.

Question 22

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

Answer 22

The anticlockwise moment (ACWM) [CWM=ACWM]

Question 23

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

Answer 23

Vertical

Question 24

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

Answer 24

Horizontal

Question 25

What is the definition of a projectile?

Answer 25

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

Question 26

During projectiles, what is the acceleration due to gravity?

Answer 26

9.81 m s‐²

Question 27

If a ball is thrown ***upwards*** what is its acceleration?

Answer 27

**-**9.81m s‐²

Question 28

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

Answer 28

9.81m s‐²

Question 29

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

Answer 29

They have the same vertical acceleration.

Question 30

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

Answer 30

They will reach the floor at the same time.

Question 31

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

Answer 31

V=s/t

Question 32

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

Answer 32

SUVAT equations.

Question 33

What is the vertical component of velocity independent to?

Answer 33

Horizontal component of velocity

Question 34

What does an object projected sideways follow?

Answer 34

A parabolic path.

Question 35

When do vertical arrows during projection get longer?

Answer 35

As the object gets closer to the ground.

Question 36

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

Answer 36

Because the horizontal velocity is constant.

Question 37

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

Answer 37

Both at the same time.

Question 38

Explain the monkey and the hunter?

Answer 38

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.

Question 39

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

Answer 39

Always

Question 40

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

Answer 40

Trigonometry.

Question 41

What is the net force also known as?

Answer 41

The resultant force

Question 42

How do you find a resultant vector?

Answer 42

Find the hypotenuse of a component triangle or find the missing side of a tip to tail diagram