问题
填空题
如图所示，已知斜面长5m，高2m，拉力为50N。利用这个装置将重为100N的物体在5s内匀速从斜面的底端拉到顶端。则拉力做功的功率为____ _ W，该装置的机械效率为______ 。
答案
100，40%
搜题请搜索小程序“爱下问搜题”
如图所示，已知斜面长5m，高2m，拉力为50N。利用这个装置将重为100N的物体在5s内匀速从斜面的底端拉到顶端。则拉力做功的功率为____ _ W，该装置的机械效率为______ 。
100，40%
How to protect your teeth 小题1: . The first of twenty being to grow when you are over six months old. The second set of thirty-two grows from the age of six until you are about twenty-one years old. 小题2: , you must drink plenty of milk and eat greens. 小题3: . Then little food will be left on or between them to cause decay(导致蛀牙). Make sure that you turn the brush and go up and down as well as brushing side ways. Use dental floss(牙线)to make sure all food is removed from in between each tooth, if you cannot brush your teeth after eating, raise them with water, or eat an apple or a carrot. 小题4: . If there is a hole in a tooth, he or she will fill it. If you do not have it filled, then the hole will grow larger. When a hole grows too big, 小题5: . It is better to keep all your second set of teeth for as long as possible. Filling a gap where a tooth has come out with a kind of bridge and using a false tooth costs a lot of money.
|