题目

Claire thinks she’s too heavy. So she decides to have a healthy lifestyle. Here is her plan.Exercise FoodRun for 40 minutes every morning.Join a sports club and swim twice a week.Go to school on foot every day.Have milk and an egg for breakfast every morning.Just have fruit for supper three times a week.Eat more vegetables and less meat for dinner.Never eat junk food.Drink eight cups of water every day. 【1】Claire will ____ for 40 minutes every morning.A. walk B. run C. eat D. read【2】Claire will swim_____ in the club.A. twice a week B. once a week C. twice a month D. once a month【3一质量为m=2kg的滑块能在倾角为θ=30的足够长的斜面上以a=2.5m/s2匀加速下滑．如图所示，若用一水平推力F作用于滑块，使之由静止开始在t=2s内能沿斜面运动位移s=4m．求：（取g=10m/s2）（1）滑块和斜面之间的动摩擦因数μ；（2）推力F的大小．