Mechanics and Materials Active Recall ANSWERS:
1. What is a scalar? 1. A quantity with only magnitude
2. A quantity with both magnitude and
2. What is a vector? direction
3. Is velocity a scalar or a vector 3. Vector
quantity?
4. Is speed a scalar or a vector 4. Scalar
quantity?
5. Is mass a scalar or a vector 5. Scalar
quantity?
6. Is force a scalar or a vector 6. Vector
quantity?
7. Is weight a scalar or a vector 7. Vector
quantity?
8. Is acceleration a scalar or a 8. Vector
vector quantity?
9. Is displacement a scalar or a 9. Vector
vector quantity?
10. Is distance a scalar or a vector 10.Scalar
quantity?
11. When can you use calculation to 11.When vectors are perpendicular
add vectors?
12. When can you use a scale 12.When vectors aren’t perpendicular
drawing to add vectors?
13. How do you calculate the 13.Pythagoras
resultant vector of two perpendicular
forces?
14. How do you find out the 14.The angle it makes with the horizontal or
direction of the resultant vector? vertical depending on the question
15. How can you combine (add or 15.A single resultant vector
subtract) vectors?
16. What does it mean to resolve a 16.Breaking it down into components
vector? horizontally and vertically
17. When a single vector is broken 17.Components
down or resolved, it is broken down into
parts called?
18. What is a coplanar force? 18.A force acting in the same plane
19. How can coplanar force be 19.Vector triangles
represented?
20. What two conditions can an 20.Stationary, constant velocity
object be in for the forces on the object
to be in equilibrium?
21. In equilibrium, what are 21.Closed vector triangles
coplanar forces represented by?
22. What are the 4 most common 22.Weight, normal reaction, friction, tension
forces on objects?
23. What is a moment? 23.A turning effect of a force
24. What equation gives you the 24.Moment = force x perpendicular distance
moment of a force? from the pivot
25. What would you use as the 25.Components of the distance
perpendicular distance to the pivot
when the force is not acting
, perpendicular to the pivot?
26.For a system to be in equilibrium, the sum
of clockwise moments about a point must
26. What is the principle of be equal to the sum of anticlockwise
moments? moments about the same point
27.A pair of forces that act in opposite
direction in the same plane which are
equal in magnitude and perpendicular to
27. What is a couple? the distance between them.
28.Forces need to act in opposite directions.
Forces must be equal in magnitude. Forces
28. What three conditions must the must be perpendicular to the distance
coplanar forces have to make a couple? between them.
29. What resultant force do couples 29.Zero resultant. Therefore they have no
produce? And therefore what acceleration. (due to f=ma)
acceleration does the object have?
30. What is the equation for the 30.Moment of a couple= force x perpendicular
moment of a couple? How is this distance between the lines of action of the
different to moments of a single force? force.
31. Can a couple have the two 31.No they have to have their own line of
forces acting from the same place, or action
line of action?
32. What is the centre of mass of an 32.The point at which the weight of the object
object? may be considered to act.
33. Where is the centre of mass 33.The centre or point of symmetry
located in a uniform regular solid
located?
34. When is an object stable in 34.When the centre of mass lies above its
terms of the position of its centre of base
mass?
35. Is an object has a wider base, 35.Lower the centre of mass and more stable
how does that affect an objects stability
and location of the centre of mass?
36. Is an object has a narrower 36.Higher the centre of mass and less stable
base, how does that affect an objects
stability and location of the centre of
mass?
37.Centre of gravity is identical to centre of
mass in a uniform gravitational field, but
as centre of mass doesn’t depend on the
gravitational field, the centre of gravity
37. How is a centre of gravity and does and would be more towards the
centre of mass different? object with the larger gravitational field.
38.Velocity at any given time for any moving
38. What is the difference between object, whereas average is total
instantaneous velocity and average displacement divided by total time of the
velocity? entire time frame of movement.
39. How do you find the 39.Draw a tangent, find the gradient
instantaneous velocity from a
displacement time graph?
40. How do you find the average 40.Divide entire displacement by entire time
velocity from a displacement time
graph?
1. What is a scalar? 1. A quantity with only magnitude
2. A quantity with both magnitude and
2. What is a vector? direction
3. Is velocity a scalar or a vector 3. Vector
quantity?
4. Is speed a scalar or a vector 4. Scalar
quantity?
5. Is mass a scalar or a vector 5. Scalar
quantity?
6. Is force a scalar or a vector 6. Vector
quantity?
7. Is weight a scalar or a vector 7. Vector
quantity?
8. Is acceleration a scalar or a 8. Vector
vector quantity?
9. Is displacement a scalar or a 9. Vector
vector quantity?
10. Is distance a scalar or a vector 10.Scalar
quantity?
11. When can you use calculation to 11.When vectors are perpendicular
add vectors?
12. When can you use a scale 12.When vectors aren’t perpendicular
drawing to add vectors?
13. How do you calculate the 13.Pythagoras
resultant vector of two perpendicular
forces?
14. How do you find out the 14.The angle it makes with the horizontal or
direction of the resultant vector? vertical depending on the question
15. How can you combine (add or 15.A single resultant vector
subtract) vectors?
16. What does it mean to resolve a 16.Breaking it down into components
vector? horizontally and vertically
17. When a single vector is broken 17.Components
down or resolved, it is broken down into
parts called?
18. What is a coplanar force? 18.A force acting in the same plane
19. How can coplanar force be 19.Vector triangles
represented?
20. What two conditions can an 20.Stationary, constant velocity
object be in for the forces on the object
to be in equilibrium?
21. In equilibrium, what are 21.Closed vector triangles
coplanar forces represented by?
22. What are the 4 most common 22.Weight, normal reaction, friction, tension
forces on objects?
23. What is a moment? 23.A turning effect of a force
24. What equation gives you the 24.Moment = force x perpendicular distance
moment of a force? from the pivot
25. What would you use as the 25.Components of the distance
perpendicular distance to the pivot
when the force is not acting
, perpendicular to the pivot?
26.For a system to be in equilibrium, the sum
of clockwise moments about a point must
26. What is the principle of be equal to the sum of anticlockwise
moments? moments about the same point
27.A pair of forces that act in opposite
direction in the same plane which are
equal in magnitude and perpendicular to
27. What is a couple? the distance between them.
28.Forces need to act in opposite directions.
Forces must be equal in magnitude. Forces
28. What three conditions must the must be perpendicular to the distance
coplanar forces have to make a couple? between them.
29. What resultant force do couples 29.Zero resultant. Therefore they have no
produce? And therefore what acceleration. (due to f=ma)
acceleration does the object have?
30. What is the equation for the 30.Moment of a couple= force x perpendicular
moment of a couple? How is this distance between the lines of action of the
different to moments of a single force? force.
31. Can a couple have the two 31.No they have to have their own line of
forces acting from the same place, or action
line of action?
32. What is the centre of mass of an 32.The point at which the weight of the object
object? may be considered to act.
33. Where is the centre of mass 33.The centre or point of symmetry
located in a uniform regular solid
located?
34. When is an object stable in 34.When the centre of mass lies above its
terms of the position of its centre of base
mass?
35. Is an object has a wider base, 35.Lower the centre of mass and more stable
how does that affect an objects stability
and location of the centre of mass?
36. Is an object has a narrower 36.Higher the centre of mass and less stable
base, how does that affect an objects
stability and location of the centre of
mass?
37.Centre of gravity is identical to centre of
mass in a uniform gravitational field, but
as centre of mass doesn’t depend on the
gravitational field, the centre of gravity
37. How is a centre of gravity and does and would be more towards the
centre of mass different? object with the larger gravitational field.
38.Velocity at any given time for any moving
38. What is the difference between object, whereas average is total
instantaneous velocity and average displacement divided by total time of the
velocity? entire time frame of movement.
39. How do you find the 39.Draw a tangent, find the gradient
instantaneous velocity from a
displacement time graph?
40. How do you find the average 40.Divide entire displacement by entire time
velocity from a displacement time
graph?
