"Newton's First Law" Motion and Force PPT (Lesson 1)

"Newton's First Law" Motion and Force PPT (Lesson 1)

The first part of the content: Practice on classification of knowledge points

Knowledge point 1 The influence of resistance on the movement of objects

1. The football rolling on the ground rolls slower and slower, and finally stops because the football is affected by _____ on the ground. This shows that the motion of an object does not require ____ to maintain, but that force is the cause of the object's motion state.

2. Does the motion of an object require force to maintain it? This problem has troubled people for a long time. In fact, by using the experimental device shown in Figure 8-1-1 to conduct experiments, and then through reasonable reasoning, we can answer this question. To ensure the success of the experiment, which of the following descriptions of the three experiments is wrong ()

A. The bevels used are the same

B. The trolleys used are the same

C. The roughness of the horizontal surface is different

D． The height of the car sliding down the slope is different.

3． Figure 8-1-2 shows the experimental device to explore the "influence of resistance on the movement of objects". Please answer:

(1) The purpose of letting the car slide down the slope and then move along the horizontal plane is to make the effects of the ____ force and _____ force on the car in the vertical direction cancel each other out, which is equivalent to the fact that the car is only affected by the force in the horizontal direction. resistance.

(2) Let the car slide down from the same position on the same slope every time, so that the car will __________ when it reaches the bottom of the slope.

(3) Choose smooth wooden boards, cotton cloth, and towels to lay on the horizontal surface at the end of the slope. It is found that the speed of a car that comes from rest at the same height of the slope decreases when it moves on different horizontal surfaces, and the smoother the horizontal surface, the slower the speed. The smaller it is _____, the distance it travels is ____.

(4) Please make a bold guess: If a car moving on a horizontal surface is not subject to resistance, it will _______________.

Knowledge point 2 Newton’s first law

4. The content of Newton's first law: All objects always maintain _____ state or ____________ state when _______________. Newton's first law is not directly derived from experiments, but is summarized through further reasoning based on a large number of empirical facts. This method of studying problems is called the __________________ method.

5. For an object that is stationary on the ground, if all external forces on it disappear, the object must be in a _____ state; for a moving object, if all external forces on it disappear, the object must be in a ____________ state. (Please choose "uniform linear motion" or "stationary")

6． As shown in Figure 8-1-3, the electric lamp hanging from the ceiling is in a stationary state. If one day, the hanging wire is suddenly disconnected and all the external forces on it disappear, the lamp will ( )

A. Vertically downward movement at a constant speed

B. vertical downward acceleration

C. stay still

D． Vertically upward motion at a constant speed

7. As shown in Figure 8-1-4, a small ball moves on a smooth arc-shaped chute AB. When the small ball moves from A to B, if all the external forces on the small ball suddenly disappear, then the small ball will ( )

A. make uniform linear motion

B. Stop exercising immediately

C. Moving slower and slower

D． moving faster and faster

Newton's first law PPT, part 2 content: comprehensive practice of regular methods

9. According to Newton's first law, we know ( )

A. When the state of motion of an object changes, it must be affected by an external force.

B. An object must be at rest if it is not acted upon by an external force

C. If the external force is removed from a moving object, the object will slowly stop.

D． The movement of objects is maintained by force

10. Regarding the application of "Newton's first law", which of the following statements is correct ( )

A. "Newton's first law" only applies to objects that are not acted upon by external forces

B. An object moving in a circular orbit will still move in a circular motion after the external force is removed.

C. An object moving in a circular orbit will move in a straight line with uniform speed after the external force is removed.

D． When a car drives to a cliff, if all external forces are removed, the car will fall off the cliff.

11． Pull the string and throw the small stone tied to the string to make it make a circular motion in the horizontal plane. If the stone rotates to the position shown in Figure 8-1-6, all external forces on the stone disappear at the same time, and the stone will move along the Which direction to fly ( )

A. Direction A

B. B direction

C. The tangent direction of the location of the stone in the picture

D． All of the above are possible

12. As shown in Figure 8-1-7, object A slides from a smooth inclined surface to a smooth horizontal surface. In this process, the relationship between the speed of the object at three points a, b, and c is ()

A. va>vb>vc

B. va＜vb＜vc

C. va＝vb＜vc

D． va=vb=vc

13. Ignoring all resistance, a big stone resting on a horizontal surface is hit horizontally by another small stone. The motion of the big stone is ()

A. always still

B. Moved a little, then stopped quickly

C. Starts moving on impact, then slowly stops

D． It starts moving when it hits, and then moves in a straight line at a constant speed.

Newton's First Law PPT, Part 3: Practical practice of high-frequency test questions

16．2018·Hengyang As shown in Figure 8-1-10, if the ball swings to the right and reaches the lowest point, the rope breaks. Assume that all forces disappear at the same time. After that, the movement of the ball is ( )

A. Falling in a straight line at a constant speed

B. Rise in a straight line at a constant speed

C. Uniform linear motion upwards

D． Make a uniform linear motion to the right in the horizontal direction

17．2017·Zaozhuang Figure 8-1-11 shows the scene of football players playing football. The following statement is correct ( )

A. When the football is flying in the air, it is only affected by air resistance.

B. As the football flies in the air, its motion state must change.

C. Kick the football with your feet and make the football fly, which shows that force is the cause of the motion of objects.

D． When the football is flying in the air, if all the forces on it disappear, it will move in a straight line with uniform speed in the horizontal direction.

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