"Balance of Two Forces" Motion and Force PPT

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"Balance of Two Forces" Motion and Force PPT

Part One Content: Basic Knowledge Key Points

Knowledge point 1: Equilibrium state

1. Which of the following objects is in equilibrium (D)

A. A rocket rising from the ground

B. Pebbles thrown vertically upward

C. A small ball rolling down a smooth slope

D. A car traveling at a constant speed on a straight horizontal road

Knowledge point 2: Conditions for the balance of two forces

2. As shown in the figure, among the following force diagrams of objects, which object can be in equilibrium is (C)

3. An object is acted upon by two forces at the same time. The three elements of these two forces are exactly the same. Then these two forces (A)

A. It must not be a balancing force B. It may be a balancing force

C. Must be a balancing force D. Unable to judge

Knowledge point 3: Application of two force equilibrium conditions

4. Xiao Ming uses a force of 10 N to push a wooden box weighing 100 N horizontally to the right, but does not push it. According to the principle of "two force balance", it can be seen that the resistance of the wooden box is 10 N, and the direction is "horizontal to the left".

5. When a parachutist falls from a high altitude, the initial speed continues to increase, and the resistance he receives is less than gravity. Later, when the athlete descends at a constant speed, the resistance he receives is equal to gravity (please fill in "greater than", "equal to" or "less than").

6. After Xiaohua watched the bicycle tightrope performance at the Science and Technology Museum, he went home and made a model, as shown in the picture. Which of the following statements is correct (B)

A. The gravity of the bicycle and the support force of the steel wire on the bicycle are a pair of balancing forces

B. The total gravity of the bicycle and the hanging object and the supporting force of the steel wire on the bicycle are a pair of balancing forces

C. The pressure of the bicycle on the steel wire and the support force of the steel wire on the bicycle are a pair of balancing forces

D. The pulling force of the bicycle on the rope and the gravity of the hook are a pair of balancing forces

Balance of Two Forces PPT, Part 2: Improvement of Comprehensive Ability

7. As shown in the figure, the gravity of the two blocks is 1 N, and they are connected and suspended by two light ropes. Then the pulling force on rope a is 2 N, and the pulling force on rope b is 1 N.

8. The crane lifts a heavy object weighing 2000 N vertically upward at a constant speed of 1 m/s, then the pulling force of the steel cable on the heavy object is 2000 N. When the crane lifts the heavy object at a constant speed of 2 m/s, the steel cable The cable tension will be equal to (optional "greater than", "equal to" or "less than") 2000 N. If the tension of the steel cable changes to 1800 N during the lifting of the heavy object, the lifting speed of the heavy object will decrease (select "increase", "decrease" or "unchanged").

9. In the following situations, the object involved is subject to a balancing force (C)

A. The Fuxing train slows down and enters the station.

B. A small ball moving in a uniform circular motion

C. Basketball resting on the ground

D. Apples falling from the tree

10. As shown in the figure, three objects with the same mass are subject to vertical upward pulling forces and are in different states: A is stationary, B is moving upwards at a constant speed at a speed of 5 m/s, and C is moving upward at a speed of 5 m/s. makes uniform linear motion downward at a speed, then the relationship between the magnitudes of F A, F B, and F C is (A)

A.F A=F B=F C

B.F A

C.F B>F A>F C

D.F C>F A>F B

11. As shown in the picture, the police are on duty on "Hot Wheels". In fact, the police use a robot transportation tool called "T-robot". The police pedal base, hand-pushed control handle, and relying on the offset of its own center of gravity can control the robot to move forward in any direction, and it can also turn on the spot, even in crowded pedestrian streets. Which of the following statements is correct (C)

A. When the police stand on the "Hot Wheel" at rest, the gravity on the "Hot Wheel" and the supporting force of the ground are a pair of balancing forces.

B. When encountering an emergency, the "Hot Wheels" cannot stop immediately because all objects are affected by inertia.

C. When the policeman drives the "Hot Wheels" in a straight line at a constant speed, using the moving "Hot Wheels" as a reference, the policeman is stationary, and the policeman's gravity and the "Hot Wheels" supporting force on him are a pair. balance force

D. When the policeman drives the "Hot Wheels" and turns on the spot at a constant speed, the policeman's motion state remains unchanged.

Balance of Two Forces PPT, Part 3: Expansion, Research and Breakthroughs

16. In the experiment of exploring the "two force balance conditions", Xiaogang designed and assembled the experimental device as shown in the figure.

(1) The teacher pointed out that the smoother the experimental tabletop, the better. The purpose is to reduce the impact of friction on the experiment;

(2) Xiaogang hangs hook codes on both ends of the thin line, and changes the pulling force by adjusting the number of hook codes. When the number of hook codes hanging on the left and right thin threads is not equal, the car will accelerate in the direction of greater pulling force. Only when the number of hook codes at both ends is equal, that is, when the car is subject to equal pulling forces to the left and right, the car will accelerate. will remain stationary. These two phenomena indicate that the two forces of balance must satisfy: ① equal in magnitude; ② opposite in direction;

(3) When the car is balancing, Xiaogang uses his hand to twist the car clockwise at an angle against the table. After letting go, the car cannot (select "can" or "cannot") balance. He observes that the car rotates counterclockwise and returns to its original position. The position is at rest. The purpose of designing this step is to explore whether two forces that are not on the same straight line can be balanced.

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For more information about the PPT courseware "Motion and Forces and Balance of Two Forces", please click on the "Movement and Forces ppt Two Forces Balance ppt" tab.

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Update Time: 2024-10-05

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 2 industry PPT template

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