Question

高中初中的英文物理题～～～大神可以用百度翻译帮的看看

A 0.48 kg block slides along a small track with elevated ends and a flat central part. The flat part has a length L = 1.18 m. The curved portions of the track are frictionless, but for the flat part the coefficient of kinetic friction is 0.101. The block is released from rest from a height h = 84 cm on the left curved portion of the track. Calculate the maximum height reached by the block on the right curved portion of the track.

Which of the following statements are true? E.g., if the first is true and the rest false, enter TFFFF.

Two balls with different masses reach the same height when shot into the air from the ground. If there is no air drag, both balls must have left the ground with the same speed.
Two objects, with different masses, have a gravitational potential energy of 100 J each; they are released from rest and fall to the ground. Both objects were released from the same height.
The formula W = F·d·cosθ can be used only if the force is constant over the distance d.
Consider a train that pulls a wagon. By Newton's third law, the wagon pulls on the train with an equal opposite force, therefore the work done by the train must be zero.
If a force acts downwards, it does negative work.

Answer 1

opposite force, therefore the work done by the train must be zero.
If a force acts downwards, it does negative work.

Answer 2

第一题
H=(mgh-mgUL)/mg=0.72m

追答

然后TFFFF，那题要解释说一声