Experimental report
Physical Inquiry Experiments: Factors Affecting the Size of Frictions
Spring dynamometer, long board, cotton cloth, towel, hooked rectangular block, weight, scale, stopwatch.
Knowledge preparation:
1. The condition of the two-force balance: the two forces acting on the same object are balanced if they are equal in magnitude, opposite in direction, and on the same line.
2. Under the action of the balance force, the stationary object remains in a stationary state, and the moving object maintains a uniform linear motion state.
3. When two objects in contact with each other, when they are in relative motion or have a tendency to move relative to each other, a force that blocks relative motion is generated on the contact surface. This force is called friction.
4. When the spring dynamometer pulls the wooden block to make a uniform linear motion on the horizontal plane, the tension is equal to the frictional force. The value of the tensile force can be read from the spring dynamometer, so that the wooden block and the horizontal plane are measured. Friction between.
Exploring the guiding inquiry guide:
The train that shuts down the engine will stop, the swinging swing will stop, the football kicked out will stop, and the moving object will stop because of the friction.
The frictional force of a moving object must have the following three conditions: 1. The objects should be in contact with each other and squeezed; 2. The contact surface should be rough; 3. The relative motion or relative motion of the two objects should occur. Three conditions are indispensable.
The point of application of the frictional force is on the contact surface, and the direction is opposite to the direction in which the object moves relative to each other. According to the three elements of force, the friction has a size in addition to the point of action and direction.
Ask the question: What is the magnitude of the friction?
Conjecture 1: The magnitude of the friction may be related to the pressure on the contact surface.
Conjecture 2: The amount of friction may be related to the roughness of the contact surface.
Conjecture 3: The magnitude of the friction may be related to the size of the contact area between the two objects that generate friction.
Inquiry program:
Use a spring dynamometer to pull the block at a constant speed so that it slides along the long plank to measure the friction between the block and the long board; change the weight placed on the block to change the block between the block and the long board The pressure; the cotton cloth is laid on the long wooden board to change the roughness of the contact surface; the contact surface of the wooden block and the long wooden board is changed, thereby changing the contact area.
Physical experiment report · chemical experiment report · biological experiment report · experimental report format · experimental report template inquiry process:
1. Pull the block at a constant speed with a spring dynamometer to measure the friction between the block and the long board: 0.7N
2. Add a 50g weight to the block and measure the friction between the block and the long board: 0.8N
3. Add a weight of 200g to the block and measure the friction between the block and the long board: 1.2N
4. Spread the cotton cloth on the wooden board and measure the friction between the wooden block and the long wooden board: 1.1N
5. Accelerate the speed of pulling the block at a constant speed, and measure the friction between the block and the long board at this time: 0.7N
6. Turn the block over so that another smaller area is in contact with the long board and measure the friction between the block and the long board: 0.7N
Explore the conclusion:
1. The amount of friction is related to the pressure acting on the surface of the object. The greater the pressure on the surface, the greater the friction.
2. The amount of friction is related to the roughness of the contact surface. The rougher the contact surface, the greater the friction.
3. The amount of friction is independent of the size of the contact surface between objects.
4. The amount of friction is independent of the speed of relative motion.
Spring dynamometer, long board, cotton cloth, towel, hooked rectangular block, weight, scale, stopwatch.
Knowledge preparation:
1. The condition of the two-force balance: the two forces acting on the same object are balanced if they are equal in magnitude, opposite in direction, and on the same line.
2. Under the action of the balance force, the stationary object remains in a stationary state, and the moving object maintains a uniform linear motion state.
3. When two objects in contact with each other, when they are in relative motion or have a tendency to move relative to each other, a force that blocks relative motion is generated on the contact surface. This force is called friction.
4. When the spring dynamometer pulls the wooden block to make a uniform linear motion on the horizontal plane, the tension is equal to the frictional force. The value of the tensile force can be read from the spring dynamometer, so that the wooden block and the horizontal plane are measured. Friction between.
Exploring the guiding inquiry guide:
The train that shuts down the engine will stop, the swinging swing will stop, the football kicked out will stop, and the moving object will stop because of the friction.
The frictional force of a moving object must have the following three conditions: 1. The objects should be in contact with each other and squeezed; 2. The contact surface should be rough; 3. The relative motion or relative motion of the two objects should occur. Three conditions are indispensable.
The point of application of the frictional force is on the contact surface, and the direction is opposite to the direction in which the object moves relative to each other. According to the three elements of force, the friction has a size in addition to the point of action and direction.
Ask the question: What is the magnitude of the friction?
Conjecture 1: The magnitude of the friction may be related to the pressure on the contact surface.
Conjecture 2: The amount of friction may be related to the roughness of the contact surface.
Conjecture 3: The magnitude of the friction may be related to the size of the contact area between the two objects that generate friction.
Inquiry program:
Use a spring dynamometer to pull the block at a constant speed so that it slides along the long plank to measure the friction between the block and the long board; change the weight placed on the block to change the block between the block and the long board The pressure; the cotton cloth is laid on the long wooden board to change the roughness of the contact surface; the contact surface of the wooden block and the long wooden board is changed, thereby changing the contact area.
Physical experiment report · chemical experiment report · biological experiment report · experimental report format · experimental report template inquiry process:
1. Pull the block at a constant speed with a spring dynamometer to measure the friction between the block and the long board: 0.7N
2. Add a 50g weight to the block and measure the friction between the block and the long board: 0.8N
3. Add a weight of 200g to the block and measure the friction between the block and the long board: 1.2N
4. Spread the cotton cloth on the wooden board and measure the friction between the wooden block and the long wooden board: 1.1N
5. Accelerate the speed of pulling the block at a constant speed, and measure the friction between the block and the long board at this time: 0.7N
6. Turn the block over so that another smaller area is in contact with the long board and measure the friction between the block and the long board: 0.7N
Explore the conclusion:
1. The amount of friction is related to the pressure acting on the surface of the object. The greater the pressure on the surface, the greater the friction.
2. The amount of friction is related to the roughness of the contact surface. The rougher the contact surface, the greater the friction.
3. The amount of friction is independent of the size of the contact surface between objects.
4. The amount of friction is independent of the speed of relative motion.
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