Unit 1: Fundamentals of mechanics - Practice Quiz

1 Newton's First Law of Motion is also commonly known as the law of:

2 According to Newton's Second Law, force is equal to:

3 Newton's Third Law states that for every action there is:

4 The force that opposes the relative motion between two surfaces in contact is called:

5 Which type of friction is generally greater for the same pair of surfaces?

6 Work is defined as the product of force and:

7 Power is best defined as the:

8 The SI unit of energy is the:

9 The turning effect of a force about a point is called:

10 The moment of a force is calculated as the force multiplied by the:

11 For a body to be in static equilibrium, the net force acting on it must be:

12 In addition to zero net force, a system in complete equilibrium must also have zero:

13 Which type of joint allows movement in only one plane, like a door hinge?

14 The joint at the shoulder that allows movement in multiple directions is a:

15 Skeletal muscles typically produce movement by:

16 The elbow joint primarily functions mechanically as a:

17 The spinal column primarily provides support and protection for the:

18 The hip joint is classified mechanically as a:

19 The knee joint mainly allows which type of movement?

20 The center of gravity of a body is the point where its entire:

21 A sprinter accelerates from rest at . According to Newton's second law, what net horizontal force must the ground exert on the sprinter?

22 When a person pushes against a wall with a force of , the wall does not move. Which of Newton's laws best explains the equal and opposite reaction force from the wall?

23 A shoe sole rests on a floor with coefficient of static friction . If the normal force is , what is the maximum static friction force before slipping occurs?

24 A physiotherapist lifts a weight vertically by in . What is the average power output? (Take )

25 A muscle contracts and shortens by while generating a constant force of . How much mechanical work does the muscle perform?

26 A force of is applied perpendicular to a wrench at a distance of from the pivot. What torque is produced about the pivot?

27 A force of acts at an angle of to a lever arm of length . What is the resulting torque about the pivot?

28 For a body to be in complete static equilibrium, which two conditions must both be satisfied?

29 A uniform beam of weight and length is supported horizontally by two supports at its ends. What upward force does each support provide?

30 Which classification best describes the type of synovial joint that allows movement in only one plane, such as flexion and extension?

31 In a muscle-tendon system, when a muscle contracts isometrically, which statement is true?

32 The biceps inserts from the elbow joint and holds a load whose weight acts from the joint. If the load weighs , what biceps force is required for equilibrium?

33 The elbow acts as which class of lever when the biceps flexes the forearm against a load held in the hand?

34 The glenohumeral (shoulder) joint offers the greatest range of motion in the body. Which joint type accounts for this multi-axial mobility?

35 When a person lifts a heavy object with a rounded (flexed) back rather than bending the knees, the load on the lumbar spine increases mainly because of what mechanical effect?

36 During single-leg stance, the hip abductor muscles must generate a large force. This is primarily because the abductor muscle moment arm is what relative to the body-weight moment arm?

37 The quadriceps insert on the tibia via the patellar tendon. The patella increases the effectiveness of the quadriceps mainly by doing what?

38 During the push-off phase of walking, the ankle behaves largely like which class of lever, with the ball of the foot as the fulcrum and the calf muscles providing effort?

39 Two point masses, at and at , lie along a line. Where is the center of gravity located?

40 To improve a patient's standing stability, which change would be most effective?

41 A person holds a ball in the hand with the forearm horizontal. The biceps inserts from the elbow joint, the center of mass of the forearm () is from the joint, and the ball is held from the joint. What is the approximate biceps force required for equilibrium?

42 A person stands in an elevator accelerating upward at . Taking , what apparent weight (normal force) does the floor exert?

43 A block on an incline just begins to slide when the incline angle reaches . What is the coefficient of static friction?

44 A athlete runs up a flight of stairs of vertical height in . Taking , what average power is developed against gravity?

45 A force of acts at a point whose position vector from the pivot is , with the force directed from the position vector. What is the magnitude of the torque?

46 During single-leg stance, the hip abductors act at a shorter moment arm than body weight about the hip joint. If the abductor moment arm is half the body-weight moment arm and body weight (minus the stance limb) is , the abductor force is approximately:

47 A two-segment limb has an upper segment (, CG at ) and lower segment (, CG at ) measured from a reference. Where is the combined center of gravity?

48 When lifting a load, the erector spinae act at a small moment arm (~) while the load moment arm about L5-S1 is large (~). For a external moment from the load, the muscle force required is approximately:

49 A uniform beam of weight rests horizontally on two supports A and B separated by length , with A at the left end. A load is placed at from A. What is the reaction at support B?

50 The patella increases the effective moment arm of the quadriceps at the knee. If removing the patella reduces the quadriceps moment arm from to , the extra muscle force needed to produce the same knee extension torque increases by what factor?

51 Based on the length-tension relationship of skeletal muscle, active tension is maximal when:

52 The deltoid muscle acting at a small angle to the humerus produces both a rotational and a large translational (dislocating) component. If the deltoid force is at to the humeral shaft, the stabilizing (compressive) component along the shaft is approximately:

53 Which change would most increase a standing person's rotational stability against tipping?

54 A three-force member is in equilibrium under non-parallel forces. For equilibrium, the three force vectors must:

55 During push-off, the Achilles tendon force acts at a moment arm of about the ankle, while the ground reaction force of acts at the ball of the foot from the ankle. What Achilles tendon force is required?

56 A synovial joint modeled as a class III lever (like most limb joints) is characterized by:

57 A ball strikes a wall at and rebounds at in the opposite direction over . What average force does the wall exert?

58 A muscle performs of positive work concentrically and absorbs eccentrically during a movement cycle. If the cycle takes , the average net mechanical power output is:

59 When a person bends forward from the hips, the whole-body center of gravity can shift outside the body. This occurs because:

60 A crate is pushed with a horizontal force on a surface with and . Once moving, what horizontal force keeps it at constant velocity, and why is it less than the force needed to start it?