起重机，吊着5×103牛顿的物体，当物体静止时，钢丝绳的拉力 ______5×103牛顿．（填大于，等于，小于）当物体匀速下降时，钢丝绳的拉力 ______5×103牛顿，当物体匀速上升时，钢丝绳拉力 ______5×103牛顿．
当物体静止时，钢丝绳的拉力和自身的重力是一对平衡力，平衡力的大小相等，所以钢丝绳的拉力等于5×103N；
当物体匀速下降时，钢丝绳的拉力和自身的重力也是一对平衡力，所以钢丝绳的拉力等于5×103N；
当物体匀速上升时，钢丝绳的拉力和自身的重力也是一对平衡力，所以钢丝绳的拉力等于5×103N．
故答案为：等于；等于；等于．
| 阅读理解。 | ||||||||||||||||||
Jackson's Clothing Store
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| 1. — Which is the cheapest (最便宜的) of all? — ______. |
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| A. A skirt. B. A T-shirt. C. A white cap. D. Pants |
| 2. — How much are two skirts and three caps? — ______. |
[ ] |
| A. ￥88. B. ￥120. C. ￥188. D. ￥214 |
| 3. In the store you can buy (买到) ______. |
[ ] |
| A. black pants B. a blue skirt C. a green cap D. two white T-shirts |
| 4. You like red and you only have ￥52. You can take ______. |
[ ] |
| A. a skirt B. a pair of shoes C. a T-shirt D. two caps |
| 5. You only have 150 yuan. You can buy ______. |
[ ] |
| A. two T-shirts and a pair of shoes B. a skirt and a pair of pants C. a skirt and two pairs of shoes D. a T-shirt and two skirts |