"High School Entrance Examination Real Questions Link" Work and Mechanical Energy PPT

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"High School Entrance Examination Real Questions Link" Work and Mechanical Energy PPT

Knowledge point 1 Gong

1．2017·Ezhou Among the following life examples, the force that does work on the object is ( )

A. A and B

B． A and C

C． B and C

D． C and D

2.2018·Zhuzhou In a basketball game, the process in which athletes do no work on the basketball is ()

A. Dribbling B. dunk

C． Wipe the board D. jump shot

3．2018·Yancheng Xiaoming picked up the physics textbook that fell on the ground and put it on the desk. The work he did on the textbook was closest to ( )

A. 0.02JB. 0.2 J

C． 2JD． 20 J

4.2017·Xiao Ming, a student from Yichang, used a horizontal thrust of 40 N to push a book box weighing 100 N forward 2 m on the level ground. After releasing his hand, the book box slid forward 1 m. Xiao Ming performed work during the whole process_ ___J, the work due to gravity on the book box is ___J.

5．2018·Yunnan As shown in Figure 11-T-8A, Zhang Hua uses a horizontal thrust F to push a wooden box placed on the horizontal ground. During this process, the size of the thrust F changes with time t as shown in Figure B As shown, the wooden box movement speed v changes with time t as shown in Figure C. Then the wooden box moves _____ (optional "constant speed" or "variable speed") in 1 to 3 s; the thrust force in 3 to 5 s The work done on the wooden box is ____J.

►Type 2 Power

6．2018·Suihua Which of the following statements about work and power is correct ( )

A. When a classmate was walking on a level road with a schoolbag on his back, he did some work on the schoolbag.

B． When a weightlifter holds the barbell stationary, the athlete does work on the barbell

C． The more work an object does, the greater its power

D． The faster an object does work, the greater its power

7.2018·Texas pulled the same object horizontally twice to make a uniform linear motion on the same horizontal plane. The distance (s)-time (t) image of the two object movements is shown in Figure 11-T-9. According to the image, Which of the following is correct ( )

A. The speed of two objects moving: v1

B． The pulling force on the object twice: F1>F2

C． The work done on the object by two pulling forces from 0 to 6 s: W1>W2

D． The power of work done on the object by two pulling forces from 0 to 6 s: P1＜P2

8．2018·Guangzhou As shown in Figure 11-T-10, OQ is the horizontal ground, and the Q of the object moving in a straight line with uniform speed from O under the action of horizontal pulling force. The pulling force F1 of the OP section is 300 N, the work done by F1 is W1, and the power is P1; the pulling force F2 of the PQ section is 200 N, the work done by F2 is W2, and the power is P2, then ( )

A. W1>W2 B. W1

C． P1>P2 D. P1

9．2017·Xinjiang As shown in Figure 11-T-11, on the level ground, a wooden box with a weight of 50 N is pushed with a horizontal thrust of 20 N, so that the wooden box moves 5 m to the right at a constant speed in 10 s. Here, During the process, the friction force on the wooden box is ____N, the work done by gravity is ____J, and the power of push work is ____W.

10．2017·Suzhou Xiaohua and her mother went shopping in the supermarket. They put 17 kg of items in a trolley and pushed them. The relationship between the speed v of the trolley and the change of time t within a certain period of time is shown in Figure 11-T- 12 shown. It is known that the trolley weighs 130 N and the resistance it experiences is 0.15 of the total weight. (g is taken as 10 N/kg)

►Type 3 mechanical energy

11．2018·Zigong When the elevator in the residential area rises at a constant speed, the elevator's ( )

A. Kinetic energy remains the same

B． Mechanical energy remains unchanged

C． Gravitational potential energy remains unchanged

D． Kinetic energy is converted into gravitational potential energy

12．2018·Linyi As shown in Figure 11-T-13, the ball in the pendulum keeps reciprocating between ABC. If the influence of resistance is not considered, the following statement is wrong ( )

A. The ball has the greatest potential energy at A and C.

B． The ball is only affected by gravity at location B

C． When the ball travels from A to B, the gravitational potential energy is converted into kinetic energy.

D． When the ball moves to position C, if all the external forces it receives disappear, it will remain stationary.

13．2018·Mianyang As shown in Figure 11-T-14, trampoline is an Olympic event. Athletes stand upright in the center of the trampoline before the start of the competition. At the start of the competition, they squat down quickly and immediately return to upright and are bounced by the trampoline. When they leave the trampoline, they remain upright. After reaching the highest point, they drop to the trampoline and then squat down quickly again when they touch the trampoline. Immediately return to upright and be bounced off the trampoline again, reaching a higher point. Ignoring air resistance, which of the following statements is correct ( )

A. Throughout the process, the athlete's mechanical energy is conserved

B． Throughout this process, the athlete's mechanical energy continues to increase

C． From leaving the trampoline to falling onto the trampoline, the athlete's mechanical energy is conserved

D． During the process from falling onto the trampoline to leaving the trampoline, the athlete's mechanical energy is conserved

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Update Time: 2024-09-23

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