题干

一个静止的质点,在0-4s时间内受到合外力F的作用,力的方向始终在同一直线上,力F随时间的变化如图所示,则质点在(     )

A:第2 s末速度改变方向

B:第2 s末位移改变方向

C:第4 s末回到原出发点

D:第4 s末运动速度为零

上一题 下一题 0.0难度 选择题 更新时间:2019-02-14 08:38:34

答案(点此获取答案解析)

D

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    Spanish River Park

    Location: 3001 Ocean Blvd.,Boca Raton.

    Admission: $16 per vehicle on weekdays,$18 on weekends and major holidays.

    Special Comments: About 95 acres,more than a half-mile of beach with lifeguards.No pets.1,680-foot nature path and large playground area.

    Food/Dining: Picnic areas with barbecue grills(烤肉架).Phone: (561)393-7811

    Restores: Restrooms and showers available.

    Red Reef Park

    Location: 1400 N.Ocean Blvd.,Boo2 Raton.

    Admission: $16 per vehicle on weekdays,$18 on weekends and major holidays.

    Special Comments: Developed beach (67 acres) with lifeguards.No alcohol or pets permitted.It offers grills and a small playground area.

    Food/Dining: Picnic areas available.Phone: (561) 393-7812

    Restrooms: Restrooms and showers available.

    South Beach Park

    Location: 400 N.Ocean Blvd.,Boca Raton.

    Admission: $15 per vehicle on weekdays,$17 on weekends and major holidays.

    Special Comments: 1,670 feet of beach,25 acres,lifeguards,955 feet of developed beach south of Boca Inlet with lifeguards.

    Food/Dining: Picnic areas available.Phone: (561) 393-7813

    Restrooms: Restrooms and showers available.

    Coconut Cove Waterpark

    Location: 11200 Park Access Road,Boca Raton.

    Admission: Adult $7; Children(4~12)$5; 3 and under free.

    Special Comments: The waterpark offers Sea Monster(怪物)walk pool,Meandering River,a waterslide and a waterfall.No alcohol or pets permitted.

    Food/Dining: Concessions.Phone: (561) 274-1140

    Restrooms: Restrooms and showers available.