physic物理问题英文41.howmuchforcemustbeappliedduringliftofftoacceleratea20-kgsatellitejustenoughtocountertheearth'sgravitationalaccelerationof9.8m/s22.youaredrivingacardownastraightroadataconstant55milesperh

Question

physic物理问题英文4
1.how much force must be applied during liftoff to accelerate a 20-kg satellite just enough to counter the earth's gravitational acceleration of 9.8m/s2
2.you are driving a car down a straight road at a constant 55 miles per hour.A.are there any forces acting on the car?if so,list them.B.Is there a net force or unbalanced force acting on the car?expain.C.if the car started to go around a long bend,still maintaining its constant speed of 55 miles per hour,is there a net force acting on the car?Explain

Answer 1

1.在一个重约 20千克 的卫星的起飞过程中,需要多大的力才能使其刚好抵消地球给它的重力加速度?
F=ma=mg
2.你以时速55英里每小时沿一条直路开车.
A. 这时车受任何力的作用吗,列出.
Friction and Air Resistance Gravity and Elasticity
B. 此时车有受到不平衡的合外力吗?
No, a=0
C. 如果车在做一个大的转弯,那么此时车受到不为零的合外力吗?
Yes, 合外力提供圆周运动向心力
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