试题与答案

一物体在外力的作用下从静止开始做直线运动,合外力方向不变,大小随时间的变化如图所

题型:不定项选择

题目:

一物体在外力的作用下从静止开始做直线运动,合外力方向不变,大小随时间的变化如图所示。设该物体在t0和2t0时刻相对于出发点的位移分别是x1和x2,速度分别是v1和v2,合外力从开始至t0时刻做的功是W1,从t0至2t0时刻做的功是W2,则

[ ]

A. x2=5x1 v2=3v1

B. x2=9x1 v2=5v1

C. x2=5x1 W2=8W1

D. v2=3v1 W2=9W1

答案:

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1-4: DADC

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题型:单项选择题

The Occupational Safety and Health Administration (OSHA) was established to protect workers from accidents and unsafe conditions on the job. There has actually been an increase in the number of job-related accidents under OSHA. This demonstrates the agency’s ineffectiveness.
Which of the following, if true, concerning the period during which the increase occurred, most seriously weakens the argument above

A.A number of job categories, excluded from the jurisdiction of OSHA in the legislation originally establishing the agency, have continued to be outside OSHA’s jurisdiction.

B.OSHA has been assigned a greater number of kinds of workplace activities to monitor.

C.There has been an increase in the total number of people at work, and the ratio of work-related deaths and injuries to size of work force has fallen in OSHA-supervised occupations.

D.Regulations issued by OSHA have met with political criticism from elected officials and the mass media.

E.(E) The increase in job-related accidents has occurred mainly in a single job category, whereas the number of job-related accidents has remained approximately constant in other categories.

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