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Describe Newton's Laws and their applications to motion.
描述牛顿运动定律及其对运动的应用。
Given F=ma, calculate the motion of an object
已知F=ma，计算物体的运动
If a 5 kg object is acted upon by a force of 20 N,
what is its acceleration? If it starts from rest,
what will be its speed after 3 seconds?
如果一个5 kg的物体受到20 N的力作用，它的加速度是多少？如果它从静止开始，3秒后的速度是多少？
What is the difference between mass and weight?
质量与重量有什么区别？
If and object has a mass of 2 kg, what is its weight
under normal Earth gravity?
如果一个物体的质量是2千克，在正常地球重力下它的重量是多少？
If a crate weighs 120 pounds, what is its mass?
如果一个箱子重120磅，它的质量是多少？
Describe static and kinetic friction and their applications
描述静摩擦和动摩擦及其应用
If the coefficient of static friction of a surface
is 0.5 and the coefficient of kinetic friction is 0.4,
then how much force will be required to set in
motion a 40 kg crate? How much force will be
required to keep it going at a constant velocity a
after starting?
如果某表面的静摩擦因数为0.5，动摩擦因数为0.4，那么要使一个40 kg的货箱开始运动，需要多少力？在开始运动后，要保持它以恒定速度运动，需要多少力？
If a large truck and a Volkswagen collide, which
is acted upon by the larger force?
如果一辆大型卡车和一辆大众汽车相撞，哪一辆受到的力更大？
If more than one force acts on an object, how do you
predict its motion from Newton's second law?
如果作用于物体的力不止一个，如何根据牛顿第二定律预测其运动？
If a 10 kg object falls in the Earth's gravity but is acted
upon by a 40 N air resistance force, what will be its
acceleration?
如果一个10 kg的物体在地球的重力下下落，但受到40 N的空气阻力力，它的加速度是多少？
What is meant by "terminal velocity" in free fall?
If air drag is proportional to the square of the velocity,
how do you calculate the terminal velocity?
如果空气阻力与速度的平方成正比，如何计算终端速度？
Does the larger Earth exert a larger
gravitational force on the smaller
Moon than it exerts on the Earth?
地球对较小的月球施加的引力是否比对地球本身施加的更大？
在自由下落中，‘终端速度’指的是什么？ |