英文物理题
Abaseballishitwithaspeedof28.0m/satanangleof49.0∘.Itlandsontheflatroofofa13.0m-...
A baseball is hit with a speed of 28.0m/s
at an angle of 49.0 ∘
. It lands on the flat roof of a 13.0m
-tall nearby building.
If the ball was hit when it was 1.4m
above the ground, what horizontal distance does it travel before it lands on the building?
Express your answer using two significant figures.
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at an angle of 49.0 ∘
. It lands on the flat roof of a 13.0m
-tall nearby building.
If the ball was hit when it was 1.4m
above the ground, what horizontal distance does it travel before it lands on the building?
Express your answer using two significant figures.
△x= 展开
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竖直方向初速度为v1=28sin49，水平初速度速度为v2=28cos49；重力加速度为g=10m/s或9.8m/s。
1、令h=13m，解关于t1的方程h=v1t1-gt1^2/2，选t1值较大的值（较小的值时球在上升阶段）
2、令h=11.6m，解关于t2的方程h=v1t2-gt2^2/2，选t2值较大的值（较小的值时球在上升阶段）
△x=v2（t2-t1）
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