Does gravity work on a football when it's flying in the air? Be accurate!

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• 1. Lift an object with a gravity of 1n by 1m, do work by 1J, do work by gravity by 1J, and the gravitational field sucks the object past If you lift an object with a gravity of 1n by 1m and do work of 1J, the gravitational field will absorb the object. However, if you want to separate the object, you also need to do work. What is the total energy of the universe Is it conservation? I don't know whether to fill in a specific number, anyway, the topic is like this
• 2. The object with weight of 1n is increased by 1m under the action of vertical tensile force. Why is the work done by tensile force not 1J
• 3. Is the work done to overcome gravity by an object with a weight of 1n, which is accelerated vertically or raised 1m vertically at a uniform speed, 1J? Is work done by overcoming gravity the work done by gravity?
• 4. When a 1n heavy object is lifted 1m high, the work done by the force on the object must be equal to 1J This sentence is wrong. Why?
• 5. I found this, ∵ 1pA * 1m & # 179; = 1n / m2 * 1m & # 179; = 1n · M = 1J work = pressure * volume
• 6. After the player kicks the football out, the work done by the football in the air is (air resistance is not included) a. How does kick work on the ball b. Gravity does work on the ball c. There is no force to work on the ball d. Not sure
• 7. When the ball with a mass of 1kg is released freely from 3m, the resistance of the ball is 0.1 times of the gravity The ball with a mass of 1kg is released freely from 3m. The resistance of the ball in motion is 0.1 times that of gravity. Assuming that the ball does not lose mechanical energy when colliding with the ground, the path of the ball from the beginning to the final rest is determined
• 8. On a smooth horizontal plane, there is a uniform thin plate with a mass of 4kg, which moves at a uniform speed of 3m / s. A 1kg ball falls into point a 20 m above the plate and rebounds to 5M high. The collision lasts for a very short time, and the gravitational impulse can be ignored 1. The elastic impulse of the plate to the ball during the collision 2. The dynamic friction coefficient between the plate and the ball is 0.08, and the velocity and direction of the plate after collision are calculated Does the ball have a horizontal speed after touch? If so, send it out 3. When the ball falls back on the board again, the distance between the ball's landing point on the board and a
• 9. There is a steel plate placed horizontally on the ground. There is a steel ball with mass m = 1kg at 3M above it. It moves vertically downward at the initial velocity V0 = 2m / s. assuming that the ball is subject to a constant air resistance f = 2n, there is no kinetic energy loss when the ball collides with the steel plate, and the ball finally stops moving (1) What's the speed of the first bounce? (2) The height of the first bounce? (3) What's the distance s it takes to stop?
• 10. At a height of 45m from the ground, a small ball with a mass of 0.1kg starts to fall freely. The instantaneous power of gravity at the end of the first second? The average power of gravity work in the second second second?
• 11. There is an apple of 2n weight. By gravity and air resistance, we can calculate the resultant force F1 and F2 when it rises and falls in the process of throwing upward Why F1 = G + F resistance? F2 = G-F resistance?
• 12. An apple with a mass of 0.2kg is thrown up vertically, and the air resistance in the process of rising and falling is 1n
• 13. Draw a graph of the gravity of the object below. G = 10 N / kg (1) a small ball with a mass of 8 kg when it falls freely in the air (excluding air resistance)
• 14. When an apple is thrown up, it is subjected to gravity and air resistance The resultant force of apple in the process of rising -- the resultant force of apple in the process of falling
• 15. As shown in the figure, the mass ratio of a and B is Ma: MB = 3:2. They were originally stationary on the flat car C. There is a compressed spring between a and B. the dynamic friction coefficient between a and B and the upper surface of the flat car is the same, and the ground is smooth. When the spring is suddenly released, there is () A. A, B, C system momentum conservation B. A, B system momentum conservation C. car remains stationary D. car moves to the right
• 16. In the "urban and rural cleaning project", an environmental sanitation team rents a number of vehicles with a carrying capacity of 8 tons to transport a batch of construction waste. If each vehicle only contains 4 tons, then 20 tons of construction waste is left; if each vehicle is full of 8 tons, then the last vehicle is not empty. How many vehicles does the environmental sanitation team rent?
• 17. The displacement time relation of a car motion is x = 8t-2t & # 178;, then the following statement is correct (multiple choice) A. The car decelerates evenly B. The initial speed of the car is 8 m / s C. The acceleration of the car is - 2m / s and 178; D. The car stopped in two seconds
• 18. P114 high school physics: 2 same objects on a smooth plane, a light spring is compressed in the middle, and the two hands are pressed to keep it still at the beginning A release both hands at the same time, the total momentum of the system is always 0 B put the left hand first, then the right hand, the total momentum is not balanced C put left hand first, then right hand, total momentum left D whenever the spring is released, the total momentum of the system remains unchanged, but not necessarily zero, as long as the spring is released and the original length is restored Which is right or wrong and why wrong
• 19. There are two cars a and B on the smooth horizontal plane There are two cars a and B on the smooth horizontal plane, and there is a light spring in the middle. Hold the car by hand and compress the spring to make the car in a static state. Take the two cars and the spring as a system. The following statement is correct: there are two cars a and B on the smooth horizontal plane, and there is a light spring in the middle, Hold the car by hand and compress the spring to make the car in a static state. Consider the two cars and the spring as a system? A after releasing the two hands, the total momentum of the system is moderate to zero B put the left hand first and then the right hand. Momentum is not conserved C put left hand first, then right hand, total momentum left D no matter when the two hands are released, the total momentum of the system will remain unchanged in the process of the spring returning to its original length, but the total momentum of the system may not be zero
• 20. If two objects M1 and M2 connected by light springs are placed on a smooth plane, the masses are not equal. If force F pushes M1, will the springs be compressed? M1 = = = = M2 use constant force F to push M1 to the left. Because the plane is smooth, M2 is not subject to friction and can't give the spring a left force, so the spring can't be compressed. At this time, they can be regarded as a whole. Is it true that the spring won't be compressed? If one side of a spring is fixed on the wall, the other end of the push will be compressed, Because the wall gives it a force. And the above problem is smooth, is it not compressed?