题干

如图所示,从同一条竖直线上两个不同点PQ分别向右平抛两个小球,平抛PQ的初速度分别为v1v2,结果它们同时落到水平面上的M点处(不考虑空气阻力).下列说法中正确的是(  )

A:一定是P先抛出的,并且v1<v2

B:一定是P先抛出的,并且v1v2

C:一定是Q先抛出的,并且v1v2

D:一定是Q先抛出的,并且v1>v2

上一题 下一题 0.0难度 选择题 更新时间:2019-01-25 08:02:03

答案(点此获取答案解析)

A

同类题1

Mobile phones and the Internet have improved our life in many ways. However, along with improvements, they also brought a number of worrying problems.
Many car accidents are caused by mobile phones. You can use many new mobile phones to get on the Internet .This can be very convenient, but some drivers get on the Internet while driving. Driving needs all our attention. By looking at their mobile phones and not at the road, these insensitive(不专注的) drivers are a danger to us all.
Many of the dangers of the Internet are well known. Children who visit websites without their parents' permission sometimes talk to older people they don't know and put themselves in great danger. People with blogs(博客) sometimes post(张贴) embarrassing photographs of people they don't know on their websites without permission. There are also people who use the Internet to get personal information that we do not want them to have.
Mobile Phones and Internet Safety Tips
l If you need to use a mobile phone when you drive, use a "hand –free" phone.
l In difficult driving situation such as rain or snow, don't use your phone at all.
l Do not make very important phone calls while driving. They take your attention off the road.
l Tell your children not to talk with anyone they do not know on the Internet.
l In an embarrassing situation, pay attention to people around you. People will be shy about taking your picture if they know you're paying attention.
l Refuse to give out any personal information on the Internet.