Vector and Scalars
Which component acts down a slope?
The force times the sine of the angle (of the slope with horizontal)
If an object is at rest on a slope, what can you say about the forces?
The forces are balanced. The friction must equal the component of the force acting down the slope, which is mgsinΘ
What other method can you use to solve vector problems?
You can solve vector problems by calculation - if it is a right angled triangle you can use pythagoras and sohcahtoa, if it is not right angled you need to use the cosine rule and the sine rule.
what are common errors in vector diagrams
* Failing to draw arrows on lines in vector diagrams *diagrams too small *inaccurate diagrams *vectors not added 'nose-to-tail' *Failing to quote a value for the direction of the resultant vector *Using pythagoras when there isn't a right angle *confusing distance and displacement *Confusing speed and velocity
What is the difference between a vector and a scalar quantity?
A scalar has magnitude (size) only, a vector has both magnitude and direction
How should the direction of the resultant be stated?
As a three figure bearing, or as an angle relative to a compass point.
How do you show the resultant on a scale drawing?
It has a double arrow, all the component vectors have a single arrow.
Is 12 m/s a speed or a velocity?
It is a speed because there no direction is stated.
Is 54 m/s NE a speed or a velocity?
It is a velocity because it has both magnitude and direction.
Does it matter which order you combine vectors in?
No - you will get the same result regardless of which vector you start with etc.
How would you tackle a problem where something is being pulled by two forces which are equal, but in different directions (like tugs or a bungee jump thing)?
Resolve one of the forces into it's components. The forces from each object acting in the direction of movement will add together, the forces acting at right angles will cancel out.
Is distance a vector or a scalar quantity?
Scalar
Is potential energy a vector or a scalar quantity?
Scalar
Is speed a vector or a scalar quantity?
Scalar
How do you resolve a force down a slope?
Split it into the parts parallel to and perperpendicular to the slope - parallel is the force times the sine of the angle, perpendicular is the force times the cosine of the angle.
What is meant by 'resolution of vectors'?
Splitting any vector into two components - one horizontal and one vertical. (Making it into a right angled triangle.
which component will not contribute to downward motion on a slope?
The component which acts perpendicular to the slope (force times the cosine of the angle to the horizontal)
How do you resolve an object of weight 30N sitting on a slope of 45 degrees?
The force parallel to the slope is 30sin45°, the force perpendicular is 30cos45° (remember sin and slope)
How would you resolve a velocity of 25m/s at 30 degrees to the horizontal?
The horizontal component would be 25cos30°, the vertical component would be 25sin30°.
What is the name of the vector which can replace a series of vectors which have been added to one another.
The resultant
Apart from the vector diagram, what else should you include when solving a problem by scale drawing?
The scale factor you are using e.g. 1cm to 10km
When combining vectors, how must they be arranged?
The vectors must lie head-to-tail, so that you can follow the path from start to finish.
Is acceleration a vector or a scalar quantity?
Vector
Is displacement a vector or a scalar quantity?
Vector
Is force a vector or a scalar quantity?
Vector
Is momentum a vector or a scalar quantity?
Vector
Is velocity a vector or a scalar quantity?
Vector
What is one disadvantage of solving vector problems by calculation?
You are not given either the cosine rule (a²= b² + c² -2bccosA) or the sine rule (a/sinA =b/sinB= c/sinC)
Is absorbed dose a vector or scalar quantity?
scalar
Is electric charge a vector or scalar quantity?
scalar
Is frequency a vector or scalar quantity?
scalar
Is half-life a vector or scalar quantity?
scalar
Is heat a vector or scalar quantity?
scalar
Is kinetic energy a vector or a scalar quantity?
scalar
Is light energy a vector or scalar quantity?
scalar
Is mass a vector or a scalar quantity?
scalar
Is power a vector or scalar quantity?
scalar
Is pressure a vector or scalar quantity?
scalar
Is refractive index a vector or scalar quantity?
scalar
Is temperature a vector or a scalar quantity?
scalar
Is time a vector or a scalar quantity?
scalar
Is volume a vector or scalar quantity?
scalar
Is wavelength a vector or scalar quantity?
scalar
Is buoyancy force a vector or scalar quantity?
vector
Is electric field strength a vector or scalar quantity?
vector
Is force a vector or scalar quantity?
vector
Is impulse a vector or scalar quantity?
vector
Is momentum a vector or scalar quantity?
vector
Is upthrust a vector or scalar quantity?
vector
Is weight a vector or a scalar quantity?
vector
