05 Vectors, Moments And Projectiles Flashcards
What is the effect a force has in a particular direction called?
The component of the force in that direction.
How do you resolve a a component of a force?
By drawing a component triangle
Does a force acting vertically have a horizontal component?
No
Does a force acting horizontally have a vertical component?
No
In vector diagrams where do arrows start?
At the head of the previous one
What is the overall effect of a combination of two or more forces called?
The resultant force
How is the resultant shown in a vector diagram?
A line drawn from the start to finish.
On a question on vector diagrams, when it askes for the direction what does that mean?
Find the angle
Why is a closed triangle of vectors a closed triangle?
Because there is no resultant force and it is in equilibrium.
What is the centre of mass?
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.)
When vectors aren’t perpendicular, how do you find the resultant …etc?
Draw a scale diagram.
What can cause turning effects?
Forces
What is the definition of the moment of a force about a point?
Force multiplied by the perpendicular distance from the point to the line of action of the force.
What is the principle of moments?
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.
A system is in equilibrium if…
•there is no resultant force acting on it AND
•there is no resultant moments acting on it
What is moments measured in?
Nm
What is tension the same as?
Force
Define a couple.
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.
Define a moments of a couple.
One force x the perpendicular distance between the lines of action of the 2 forces.
What is a moment of a couple also known as?
A torque
When an object is in equilibrium, what is the sum of the upwards force equal to?
The sum of the downwards force.
When in equilibrium, what is the clockwise moment (CWM) equal to?
The anticlockwise moment (ACWM) [CWM=ACWM]
In suvat equations, is the ‘s’ vertical or horizontal?
Vertical
In the equation s=v/t, is the ‘s’ vertical or horizontal?
Horizontal
What is the definition of a projectile?
A moving object on which the only force acting on it is weight.
During projectiles, what is the acceleration due to gravity?
9.81 m s‐²
If a ball is thrown upwards what is its acceleration?
-9.81m s‐²
If a ball is dropped downwards, what is the acceleration?
9.81m s‐²
If one object is projected horizontally and another identical object is allowed to fall vertically, what can be concluded about their acceleration?
They have the same vertical acceleration.
If one object is projected horizontally and another identical object is allowed to fall vertically, which will hit the floor first?
They will reach the floor at the same time.
When finding a horizontal projection, what equation should you always use?
V=s/t
When calculating vertical projection, what type of equation should you always use?
SUVAT equations.
What is the vertical component of velocity independent to?
Horizontal component of velocity
What does an object projected sideways follow?
A parabolic path.
When do vertical arrows during projection get longer?
As the object gets closer to the ground.
During a horizontal projection, why are the horizontal arrows always the same length?
Because the horizontal velocity is constant.
If 1 ball is projected and another is in free fall, which ball will hit the ground first?
Both at the same time.
Explain the monkey and the hunter?
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.
When firing an object at an angle, when is the horizontal velocity constant?
Always
When firing an object at an angle and you have that velocity, how do you find the horizontal or vertical velocity?
Trigonometry.
What is the net force also known as?
The resultant force
How do you find a resultant vector?
Find the hypotenuse of a component triangle or find the missing side of a tip to tail diagram
