1
1
The 1000 newton weight of a pile driver falls freely from rest; it drops 25 meters,strikes a steel beam,and drives it 3 centimeters into the ground.The speed of the weight just before hitting the beam is ,in meters per second,approximately?
2
The operator of a boat wishes to cross a 5 kilometer-wide river that is flowing the the east at 10 meters persecond.He wishes to reach the exact point on the opposite shore 15 minutes after starting.At what speed and in what direction should the boat travel?
11.2m/s at 63.4 W of N
The 1000 newton weight of a pile driver falls freely from rest; it drops 25 meters,strikes a steel beam,and drives it 3 centimeters into the ground.The speed of the weight just before hitting the beam is ,in meters per second,approximately?
2
The operator of a boat wishes to cross a 5 kilometer-wide river that is flowing the the east at 10 meters persecond.He wishes to reach the exact point on the opposite shore 15 minutes after starting.At what speed and in what direction should the boat travel?
11.2m/s at 63.4 W of N
英語人氣：586 ℃時間：2020-05-14 08:37:56
優(yōu)質(zhì)解答
BARRON上的題吧 1能量守恒,1/2mvv=mgh ,即1/2*100kg*v*v=100kg*g*25m ,v為根號下500,所以是22 2意思是要河的正對面,即水平方向沒有位移.合速度是垂直于岸的.合速度為 5000m/900s=5.5,船速度=根號下5.5*5.5+10*10 約...
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