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Solving Physics Workbook Grade 6 Exercise 7: Understanding the Effects of Forces
Exercise 7.1 on page 25 of the Physics Workbook (SBT) Grade 6
When a ball hits a wall, the force exerted by the wall on the ball will result in what outcomes?
* Answer:
Choose D.
* Explanation:
The force exerted by the wall on the ball results in both deforming the ball and altering its motion.
Exercise 7.2 on page 25 of the Physics Workbook (SBT) Grade 6
Among the following objects and phenomena, indicate the object experiencing force and the outcome caused by the force acting on it:
a) A freshly poured concrete slab with imprints of chicken feet (H.7.1a).
b) A crushed aluminum can lying beneath a fallen bamboo ladder on the ground (H.7.1b).
c) During a thunderstorm, a poplar leaf being blown upward (H.7.1c).
d) A low-hanging branch of a poplar tree snapped (H.7.1c).
e) A fishing float suddenly sinking into the water.
1. Explanation: a) The chicken leg applies force on the concrete slab resulting in a depression on the concrete. b) The leaning ladder exerts force on the aluminum pot causing it to deform. Exercise 7.3 Page 25 Physics Workbook Grade 6
Which of the following objects have undergone changes in motion? Not undergone changes? (Mark X in the boxes you choose). a) A bicycle suddenly applies brakes and comes to a stop. b) A motorcycle in motion suddenly accelerates, speeding up. c) A grasshopper sitting on a rice leaf suddenly jumps and flies away. d) An airplane flying straight at a speed of 500km/h e) A box placed on a train carriage is slowing down and eventually stops.
Bài 7.3 trang 25 Sách bài tập (SBT) Vật lí 6
Chuyển động của các vật nào dưới đây đã bị biến đổi? Không bị biến đổi?
(Đánh dấu X vào các ô mà em chọn).
a) Một chiếc xe đạp đang đi, bỗng bị hãm phanh, xe dừng lại.
b) Một chiếc xe máy đang chạy, bỗng được tăng ga, xe chạy nhanh lên.
c) Một con châu chấu đang đậu trên một chiếc lá lúa, bỗng đập càng nhảy và bay đi.
d) Một máy bay đang bay thẳng với vận tốc 500km/h
e) Một cái thùng đặt trên một toa tàu đang chạy chậm dần, rồi dừng lại.
1. Solution Guide: a) Undergoes change b) Undergoes change c) Undergoes change d) Does not undergo change e) Undergoes change
Provide an example demonstrating a force acting on an object causing a change in its motion and another example demonstrating a force acting on an object causing deformation.
Bài 7.4 trang 26 Sách bài tập (SBT) Vật lí 6
Hãy nêu một thí dụ chứng tỏ lực tác dụng lên một vật làm biến đổi chuyển động của vật đó và một thí dụ chứng tỏ lực tác dụng lên một vật làm biến dạng vật đó
1. Solution Guide: - A person pushes a car, the car gradually accelerates. - Squeezing a spring forcefully deforms it.
Phenomenon proving that while a ball is ascending, there is always a force acting on it (H.7.2)
Bài 7.5 trang 26 Sách bài tập (SBT) Vật lí 6
Hiện tượng gì chứng tỏ rằng trong khi một quả cầu đang bay lên cao thì luôn luôn có một lực tác dụng lên quả cầu (H.7.2)
To solve this problem, follow these steps:
The flying ball occasionally changes its direction of flight. This phenomenon indicates that there is an air force acting on the ball, altering its motion while flying upward.
Exercise 7.6 on page 26 of the Physics Exercise Book (PEB) Grade 6
A rock is thrown forcefully at a mound of earth. The force exerted by the rock on the mound of earth:
* Answer:
Choose option A
* Explanation:
A rock is thrown forcefully at a mound of earth. The force exerted by the rock on the mound of earth only deforms the mound of earth.
Exercise 7.7 on page 26 of the Physics Exercise Book (PEB) Grade 6
Identify the incorrect statement.
Striking a hammer against an anvil. The force exerted by the hammer on the anvil and the force exerted by the anvil on the hammer will cause
A. the hammer to deform slightly
B. the anvil to deform slightly.
c. the motion of the hammer to change.
D. the motion of the anvil to change.
* Answer:
Choose option D
* Explanation:
Striking a hammer against an anvil. The force exerted by the hammer on the anvil and the force exerted by the anvil on the hammer will cause the anvil to deform slightly, not change the motion of the anvil. Therefore, the incorrect statement is D.
Exercise 7.8 on page 26 of the Physics Exercise Book (PEB) Grade 6
Identify the incorrect statement
Two buffaloes clash with each other, with no clear winner.
A. The force exerted by one buffalo on the other is equally strong.
B. The force exerted by one buffalo on the other is two balanced forces.
C. These forces can cause the heads of the buffaloes to have rough skin.
D. The force exerted by one buffalo cannot push back the other buffalo.
* Answer:
Choose option B
* Explanation:
Two buffaloes clash with each other, with no clear winner. The force exerted by one buffalo on the other is not two balanced forces because these forces act on two different buffaloes.
So the incorrect statement is B.
Exercise 7.9 on page 27 of the Physics Exercise Book (PEB) Grade 6
A student drops a ball from above and observes that the ball falls faster and faster. Which statement made by the student is correct?
A. The ball is no longer subject to any force because we released it.
B. The ball falls faster and faster, so it must be subject to a force, and this force can only be the force of our hand.
C. The ball is a heavy object, so like all heavy objects, when dropped from above, they all fall slower and slower, even though they are not subject to any force.
D. The ball has been released, so it is no longer subject to the force of the hand. However, the ball falls faster and faster, so it must be subject to a force, which cannot be the force of our hand but another force.
* Answer:
Choose option D.
* Explanation:
The correct statement is: The ball has been released, so it no longer experiences the force of the hand. However, the ball falls faster and faster, indicating it experiences another force, which cannot be the force of our hand but another force. Later, we know this force is the gravitational force of the Earth.
Exercise 7.10 page 27 Physics Exercise Book (PEB) Grade 6
Using both hands to stretch a rubber band, then keeping the rubber band still.
a) Identify the forces acting in this situation and on which objects.
b) Compare the direction, orientation, and strength of these forces. Knowing the rubber band always lies horizontally.
* Answer:
a) The forces acting on the rubber band include: the pulling force of the right hand, the pulling force of the left hand, and gravity.
The forces acting on the right hand and the left hand are the two pulling forces of the rubber band.
b) Comparing the direction, orientation, and strength of these forces:
- Because gravity is negligible, the forces acting on the rubber band are: the pulling force of the right hand and the pulling force of the left hand, both horizontally oriented, opposite in direction, and equal in strength, these are two balanced forces.
- The forces acting on the right hand and the left hand are the two pulling forces of the rubber band, both horizontally oriented, opposite in direction, and equal in strength, but these are not balanced forces because they act on two different hands.
Exercise 7.11 page 27 Physics Exercise Book (PEB) Grade 6
Choose the incorrect statement. Force is the cause of making an object
A. moving uniformly to accelerate
B. moving straight to curve
C. moving uniformly to continue moving uniformly
D. moving straight to stop
* Answer:
Choose C
* Explanation:
Force is the cause of changes in motion for objects. So, the incorrect statement is: Force is the cause of making an object moving uniformly to continue moving uniformly.
Exercise 7.12 page 27 Physics Exercise Book (PEB) Grade 6
Tie one end of a rubber band to a support and hang a nylon bag containing water from the other end. Based on which of the following signs can we determine that the nylon bag containing water exerts a force on the rubber band
A. The nylon bag containing water does not fall
B. The nylon bag containing water is deformed
C. The rubber band stretches
D. All three signs above
* Answer:
Choose option C
The indication that the nylon bag containing water exerts a force on the rubber band is the stretching of the rubber band.
