P8 Forces in Balance

P8 Forces in Balance

1. Which of these is not true for a scalar quantity?

a) It has magnitude (size) and direction.
b) It has a unit.
c) It has magnitude (size) only.
d) The sum of scalar quantities can be found by simply adding them together.

2. Which of these is true for a vector quantity?

a) It has magnitude (size) and direction.
b) It does not need a unit.
c) It has magnitude (size) only.
d) The sum of vector quantities can be found by simply adding them together.

3. Which of the following quantities is a vector and not a scalar?

a) distance
b) speed
c) displacement
d) mass

4. Which of the following quantities is a scalar and not a vector?

a) force
b) mass
c) acceleration
d) velocity

5. When an arrow is used to represent a vector quantity, what does the length of the arrow represent?

a) the magnitude of the vector
b) distance from the pivot
c) the length of the vector
d) the time the vector acts for

6. Which of the following is not a contact force?

a) air resistance
b) friction
c) tension
d) weight

7. Which of the following is a contact force?

a) gravitational
b) magnetic
c) normal
d) electrostatic

8. Which of the following statements best describes an interaction pair between object A pushing object B?

a) The force of A on B is equal and opposite to the force of B on A.
b) The forces on A and B are equal and opposite.
c) The resultant force is given by adding the forces on A and B.
d) The resultant force is zero as the force on A is balanced by the force on B.

9. Which of these diagrams correctly shows the interaction pair when the blue box is pulling the orange box?

a) A
b) B
c) C
d) D

10. Which of the following forces is caused by the gravitational field around the Earth?

a) lift
b) weight
c) drag
d) friction

11. Which of these statements is always true about the weight of a 1kg mass?

a) The weight depends on the gravitational field strength.
b) The weight is a fixed value as long as the mass is 1 kg.
c) The weight is always 9.8 N
d) The weight is not related to the mass it only depends on the gravitational field strength.

12. Which of the following is not a correct equation linking mass (m), weight (W) and gravitational field strength (g)?

a) W=mg
b) g=W/m
c) m=g/W
d) m=W/g

13. Which of the following is the standard unit of weight?

a) kg
b) g
c) J
d) N

14. Which of the following is the standard unit of mass?

a) N
b) g
c) m
d) kg

15. Which of the following is the standard unit of gravitational field strength?

a) kg/N
b) N kg
c) N/kg
d) g

16. Which of the following statements is the best description for centre of mass of an object?

a) The point within in an object that is furthest from its surface.
b) the single point where the weight or mass of an object can be considered to be concentrated.
c) The point in the middle of the object.
d) The point in the object where its mass is generated.

17. What is the relationship between mass and weight assuming that gravity is constant?

a) mass is inversely proportional to weight
b) mass is directly proportional to weight
c) mass and weight are independent
d) the product of mass and weight is a constant

18. An object of mass 5 kg is in a gravitational field of 10 N/kg. Calculate the weight of the object?

a) 0.5 N
b) 15 N
c) 50 N
d) 25 N

19. An object of weight 200 N is in a gravitational field of 10 N/kg. Calculate the mass of the object?

a) 20 kg
b) 2 kg
c) 2000 kg
d) 20 g

20. Which of the following is the best description of a resultant force?

a) The result of the forces on an object
b) The single force that will have the same effect on an object as a number of individual forces.
c) The result of adding up the forces on the objects in an interaction pair.
d) The single force that is added to the forces on an object to generate a result.

21. What is the resultant of the following two forces? 5 N to the left and 3 N to the right?

a) 3 N to the right
b) 8 N to the left
c) 2 N to the left
d) 8 N to the right

22. Which force in the diagram is the resultant of the two blue forces?

a) A
b) B
c) C
d) D

23. Which force in the diagram is the resultant of the three blue forces?

a) A
b) B
c) C
d) D

24. Which two forces can the orange force be resolved into?

a) A and C
b) C and D
c) B and E
d) C and E

25. Which two forces can the red force be resolved into?

a) B and C
b) It can’t be done
c) E and C
d) A and D

26. What term is used in physics to mean the turning effect of a force?

a) moment
b) momentum
c) pivot
d) leverage

27. Which of these is not a correct relationship between the moment of a force (M) the magnitude of a force (F) and the perpendicular distance the force acts from the pivot (d)?

a) M = Fd
b) M = F/d
c) F = M/d
d) d = M/F

28. Which is the following statements is the best description an object that is balanced?

a) There are no moments to unbalance the object.
b) There is no pivot so the object can’t fall.
c) The forces causing the moments are equal and opposite so the cancel out.
d) The clockwise moments about a pivot equal the anticlockwise moments about the pivot.

29. If a large radius gear is connected to a small radius gear which of the following is not true?

a) The small gear will rotate faster than the large gear.
b) The turning force on the large gear will be greater than the small gear.
c) The gear are connected so will have the same turning force and will rotate as the same rate.
d) The moments acting on the two gears are the same size.

30. Calculate the moment of a 4 N force acting 2 m from a pivot.

a) 2 Nm
b) 6 Nm
c) 16 Nm
d) 8 Nm

31. Two children sit on a see-saw. Bill has a mass of 20 kg and sits 60 cm from the pivot. Ben has a mass of 15 kg. How far must Ben sit from the pivot to balance the see saw?

a) 40 cm
b) 100 cm
c) 80 cm
d) 120 cm

32. Ben’s dog now jumps into his lap. To balance the see saw he (and his dog) have to move to 50cm from the pivot. What is the mass of Ben's dog?

a) 7 kg
b) 8 kg
c) 9 kg
d) 10 kg

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