A ball is thrown vertically upwards, reaches its highest point, then drops down to the ground, bounces once,reaches a height of 1.2 m, then falls again and finally rests on the grass. At which one or more times is the gravitational force on the ball zero?

Question

BlackTom AI · Accepted Answer

To determine when the gravitational force on the ball is zero, we need to recall a basic fact: gravity acts on the ball at all times unless the ball has no mass or is in a zero-gravity environment. In this scenario, the ball is under Earth's gravity the entire motion: rising, stopping, descending, bouncing, and resting.

Option a: At the highest point it reached. At the top the ball has zero vertical velocity, but gravity is still pulling downward. Therefore the gravitational force is not zero here.

Option b: When the ball had bounced up to a height of 1.2 m. During the ascent after the bounce, gravity continues to act downward; the height at which the velocity may be momentarily small does not eliminate gravity.

Option c: The ball always experiences the force of gravity. This aligns with Newtonian physics: gravity acts continuously on a mass near the Earth, regardless of its motion phase. This is a true statement.

Option d: Whenever it was moving down. While the ball is moving downward, gravity remains downward; the force is not zero.

Option e: At the exact instant the ball was thrown up. The motion may involve a change in velocity, but gravity still acts downward at that instant, so the force is not zero.

Option f: When the ball rested on the grass. Even at rest, gravity pulls the ball downward toward the ground; the force is still present.

Option g: At the instant the ball hit the ground for the first time. Contact forces (normal reaction) may be present, but gravity is still acting downward as well; the gravitational force is not zero.

Option h: Before the ball was thrown. Prior to release, gravity already acts on the ball just as it does during any other time near Earth.

Option i: Whenever the ball was moving up. While moving upward, gravity pulls downward; the force is not zero.

In summary, the only correct statement is that gravity always acts on the ball throughout its motion; none of the other listed moments render the gravitational force zero.

A ball is thrown vertically upwards, reaches its highest point, then drops down to the ground, bounces once,reaches a height of 1.2 m, then falls again and finally rests on the grass. At which one or more times is the gravitational force on the ball zero?

查看解析

登录即可查看完整答案

类似问题

Suppose you landed on a planet with 3 times the mass and 3 times the radius of Earth. What would your relative weight be?

Question at position 36 The attraction between Earth and the Moon is an example of ________ force.electricalgravitationaltectonicmagnetic

Why does an object have the gravitational force and what is the direction of the force?

Two objects move toward each other because of gravitational attraction. As the objects get closer and closer, the force between them _____.

Why does the Sun have such a strong gravitational pull?

Why does the Sun have such a strong gravitational pull?

A ball is thrown vertically upwards, reaches its highest point, then drops down to the ground, bounces once,reaches a height of 1.2 m, then falls again and finally rests on the grass. At which one or more times is the gravitational force on the ball zero?

哪个课堂论点最能将引力结合的概念与太阳系中观测到的运动联系起来？

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单