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Solving Exercise SBT Physics Grade 6 Exercise 15: Lever
Exercise 15.1 page 49 Physics Exercise Book (SBT) Grade 6
Choose the appropriate words to fill in the blanks:
a) A lever always has........... and has......... acting on it.
b) When the distance from the fulcrum to the point of application of force by the person is greater than the distance from the fulcrum to the point of application of force by the object being lifted, this lever is advantageous in terms of............
* Solution:
a) A lever always has a fulcrum and has forces acting on it.
b) When the distance from the fulcrum to the point of application of force by the person is greater than the distance from the fulcrum to the point of application of force by the object being lifted, this lever is advantageous in terms of force.
Exercise 15.2 page 49 Physics Exercise Book (SBT) Grade 6
Use a crowbar to lift heavy objects (H.15.1).
Where should the fulcrum be placed to lift the object most easily?
A. At X. B. At Y.
C. At Z. D. At the midpoint between Y and Z.
* Answer:
Choose A.
* Explanation:
Place the fulcrum at X to lift the heavy object with the crowbar because then the lever arm is the largest.
Exercise 15.3 page 49 Physics Exercise Book (SBT) Grade 6
Fill in the symbols O (fulcrum), O1 (point of application of force by the object), and O2 (point of application of force by the person) at the appropriate positions on the levers in figure 15.2. Among these levers, which one is advantageous in terms of force?
* Solution:
Among the tools mentioned, the paper cutter (figure c), and the bottle opener (figure d) are advantageous in terms of force.
Exercise 15.4 page 49 Physics Exercise Book (SBT) Grade 6
Using a spoon and a coin can both open the box lid. Which object will make it easier to open? Why?
* Solution
Using a spoon will make it easier because the lever arm is longer.
Exercise 15.5 page 50 Physics Exercise Book (SBT) Grade 6
Hands, feet of human beings function like levers. The arm bones, leg bones are levers, the bone joints are fulcrums, while the muscles generate force.
To lift a 20N heavy object, the muscles need to exert a force of 160N. However, if the muscles contract by just 1cm, the object is already lifted by 8cm. It is said that, although not advantageous in terms of force, using this lever is advantageous in terms of distance (H. 15.4).Think about the movements of the legs, arms... and find out which levers are in your body?
* Solution:
In the body, many parts operate on the principle of levers including the bones and muscles of the arms (mentioned above), the calf, the fingers, feet, head, and neck...
Exercise 15.6 page 50 Physics Exercise Book (SBT) Grade 6
Which of the following scales is not an application of a lever?
A. Roberval scale. B. Stopwatch scale.
C. Beam scale. D. Dumbbell scale.
* Solution:
Choose B
* Explanation:
Among the scales mentioned, the stopwatch scale is not an application of a lever because it is an application of elastic force.
Exercise 15.7 page 50 Physics Exercise Book (SBT) Grade 6
Which of the following tools is not an application of a lever?
A. Nail puller hammer.
B. Water well pump handle.
C. Bottle opener.
D. Device attached to the top of a flagpole used to raise and lower the flag.
* Answer:
Choose D
* Explanation:
The device attached to the top of a flagpole used to raise and lower the flag is typically a winch, so it does not operate on the principle of a lever.
Exercise 15.8 page 50 Physics Exercise Book (SBT) Grade 6
In figure 15.5, the ancient Egyptians are using a device constructed based on the principle of
A. inclined plane.
B. lever.
C. lever combined with a pulley.
D. inclined plane combined with a lever.
* Answer:
Choose B
In figure 15.5, the ancient Egyptians are using a device constructed based on the principle of a lever.
Exercise 15.9 page 51 Physics Exercise Book (SBT) Grade 6
In figure 15.6, a lever with fulcrum O is used to lift an object of weight P. Which lever force below is most advantageous? Knowing that the arrow indicates the longer the force, the greater the force intensity.
A. Force F1 B. Force F2.
C. Force F3. D. Force F4.
* Answer
Choose D
Using lever force F4 is most advantageous because the lever arm for this force is the longest segment OD.
Use the following characteristic of the lever to answer questions 15.10 and 15.11: In a lever, if O2O is greater than O1O by how many times, then F2 is smaller than F1 by how many times.|
Exercise 15.10 page 51 Physics Exercise Book (SBT) Grade 6
To lift a 2000N heavy object with a force of 500N, you must use a lever with
A. O2O = O1O. B. O2O > 4O1O.
C. O1O = 4O2O. D. 4O1O > O2O > 2O1O.
* Answer:
Choose B
* Explanation:
To lift a 2000N heavy object with a force of 500N, you must use a lever with lever arms O2O > 4O1O
Exercise 15.11 page 51 Physics Exercise Book (SBT) Grade 6
A person carrying water. The first barrel weighs 20kg, the second barrel weighs 30kg. Let the point of contact between the shoulder and the carrying pole be O, the point where the first barrel hangs on the carrying pole be O1, and the point where the second barrel hangs on the carrying pole be O2. Ask OO1 and OO2 which values make the water load balanced?
A. OO1 = 90cm, OO2 = 90cm.
B. OO1 = 90cm, OO2 = 60cm.
C. OO1 = 60cm, OO2 = 90cm.
D. OO1 = 60cm, OO2 = 120cm.
* Answer:
Choose B
* Explanation:
To balance the water load, OO1 and OO2 have values OO1= 90cm, OO2 = 60cm. Because when P1d1 = P2d2 ⇒ 200.90 = 300.60
Exercise 15.12 page 51 Physics Exercise Book (SBT) Grade 6
A student wants to design a water lifting lever from the well according to the principle of the lever (H.15.7) with the following requirements:
1. Using a force of 40N to pull a water bucket weighing 140N is feasible.
2. O2O = 2O1O (O2O represents the distance from the pulling point to the support; O1O is the distance from the bucket's attachment point to the support). How heavy must an object hung at the end of the rope be at least? Knowing that the intensity of force F1 is greater than the intensity of force F2 by how many times, then O1O is smaller than O2O by how many times.
* Solution:
To use a force of 40N to pull a water bucket weighing 140N and with the length O2O = 2O1O, you must hang an object at the end of the rope with a minimum weight of m such that:
40.O2O + 10m O2O = 140.O1O = 70.O2O => 40 + 10m = 70 => m = 3kg
Exercise 15.13 page 52 Physics Exercise Book (SBT) Grade 6
Figure 15.8 illustrates two individuals using a lever to lift the same heavy object. If F1 represents the pressing force of the person in figure 15.8a, and F2 represents the lifting force of the person in figure 15.8b, then:
A. F1 > F2 because B1O1 < B2O2 and A1O1 < B2O2.
B. F1 < F2 because B1O1 > B2O2 and A1O1 < B2O2.
C. F1 > F2 because the first lever is longer.
D. F1 = F2 because both levers are of equal length.
* Solution:
Choose A
* Solution:
If F1 represents the force in figure 15.8a, and F2 represents the force in figure 15.8b, then because B1O1 < B2O2 and A1O1 = A2O2, F1 > F2.
Exercise 15.14 on page 52 of Exercise book (Physics 6)
Figure 15.9 depicts two individuals carrying an equally heavy object.
Which figure shows a greater intensity of pulling force by the person's hand?
* Solution:
Person B must exert a greater force because the lever arm is smaller.
