Answer: Erosion or water level rising
Explanation: Erosion happens when water goes against a rock and breaks it down little by little so these mountains may have once been above water but became eroded. Also, people might’ve added so much pollution into the ocean that the water level rose or there was an increase in the population of large animals. Sorry for my very long answer lol
Answer:
a) 70 N, b) b. Each initially applied a force bigger than static friction to get the box moving and accelerating, then when the desired final speed was achieved they reduced the force to make the net force zero.
Explanation:
a) A constant speed means that magnitude of friction force is equal to the magnitude of the external force. The friction force is directly proportional to the normal force, which is equal to the weight of the box. Therefore, the magnitude of the force is 70 N.
b) Alice used initially a greater force to accelerate the box up to needed speed and later reduced the external force to keep speed constant. The right choice is option b.
Any one trial might have been done incorrectly.
