作业帮美国大学物理题,但我物理超差.帮帮忙哥哥姐姐
来源：学生作业帮 编辑：作业帮 分类：英语作业 时间：2024/05/18 13:27:51
美国大学物理题,但我物理超差.帮帮忙哥哥姐姐
第一题：A second baseman tosses the ball to the first baseman,who catches it at the same level from which it was thrown.The throw is made with an initial speed of 19.0 m/s at an angle of 35.0° above the horizontal.(Neglect air resistance.)
How long is the ball in the air?
第2题：Babe Didrikson holds the world record for the longest baseball throw (296 ft) by a woman.For the following questions,assume that a ball is thrown at an angle of 45.0° above the horizontal,that it travels a horizontal distance of 279 ft,and is caught at the same level from which it was thrown.
(a) What is the ball's initial speed?
(b) How long is the ball in the air?
第一题：A second baseman tosses the ball to the first baseman,who catches it at the same level from which it was thrown.The throw is made with an initial speed of 19.0 m/s at an angle of 35.0° above the horizontal.(Neglect air resistance.)
How long is the ball in the air?
第2题：Babe Didrikson holds the world record for the longest baseball throw (296 ft) by a woman.For the following questions,assume that a ball is thrown at an angle of 45.0° above the horizontal,that it travels a horizontal distance of 279 ft,and is caught at the same level from which it was thrown.
(a) What is the ball's initial speed?
(b) How long is the ball in the air?
the first one
in the vertical direction,the ball up and down ,and to the same level,so the time t=2*19.0*sin35.0/g（including up time and down time)
the second one
(2)279*0.3048=S(distance)
assume initial speed is v,
horizontal direction vcosa=S/t
vertical direction t=2v*sina/g
so v=根号（gs）
t=根号（2s/g)
in the vertical direction,the ball up and down ,and to the same level,so the time t=2*19.0*sin35.0/g（including up time and down time)
the second one
(2)279*0.3048=S(distance)
assume initial speed is v,
horizontal direction vcosa=S/t
vertical direction t=2v*sina/g
so v=根号（gs）
t=根号（2s/g)