Falling Objects and Gravity

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Questions and Answers

What is the formula for drag force?

0.5 x d x v x A x C

0.5 x d x v2 x A x C (correct)

0.5 x d x v x A

0.5 x d x v2 x A

Terminal velocity is the highest velocity attainable by an object as it falls through a fluid.

True

What is work done?

Work done is the amount of energy transferred when a force is applied to an object, causing it to move through a distance.

The unit of work done in SI units is _______.

Joule Signup and view all the answers

What are the factors that affect the amount of work done?

Magnitude of force applied, displacement of the body, and angle between the displacement and force applied Signup and view all the answers

Work is said to be done only when a body is displaced under the application of force perpendicular to the direction of force.

False Signup and view all the answers

Match the following types of forces with their descriptions:

Drag Force = Force acting on an object falling through a fluid Buoyancy = Upward force exerted by a fluid on an object partially or fully submerged Gravity = Downward force acting on an object Signup and view all the answers

What is the formula for work done?

W = F x d x cosθ Signup and view all the answers

Who showed that objects of the same size and shape but with different masses fall at the same time towards Earth?

Galileo Galilei Signup and view all the answers

The acceleration of free fall is 10m/s2 for all objects.

False Signup and view all the answers

What is the characteristic of free falling objects?

They accelerate downwards at a rate of 9.8ms-2 and do not encounter any air resistance. Signup and view all the answers

The drag force depends on the _______________________ of the falling body.

speed Signup and view all the answers

Match the following scientists with their contributions to the study of falling objects:

Aristotle = Believed that the speed of falling objects depends on their weight Galileo Galilei = Disproved Aristotle's idea with an experiment Isaac Newton = Explained the force of gravity and its effects on falling objects Signup and view all the answers

What is the force that opposes the force of gravity on an object falling through the air?

Drag force Signup and view all the answers

The drag force is directly proportional to the density of the air.

True Signup and view all the answers

What is the acceleration due to gravity?

9.8m/s2 Signup and view all the answers

Study Notes

Force on Falling Objects

Aristotle believed that the speed of falling objects depends on their weight, but his idea was unclear.
Galileo Galilei proved that objects of the same size and shape, but with different masses, fall at the same time towards the Earth when dropped from the same height, disproving Aristotle's idea.
Isaac Newton demonstrated and explained why objects fall towards the Earth, citing two forces: the weight of the object and air resistance.

Experiment on Force on Falling Objects

In an experiment, a coin and a feather of roughly the same surface area were made to fall in a plastic tube.
With air in the tube, the feather fell much more slowly than the coin.
After pumping out the air, the feather fell much more rapidly, almost as fast as the coin.

Key Points

All bodies fall towards the Earth at a speed of 9.8 m/s², regardless of their size and mass.
Acceleration due to gravity (g) is 9.8 m/s².

Characteristics of Free Falling Objects

Free falling objects do not encounter air resistance and accelerate downwards at a rate of 9.8 m/s².
Free fall occurs when an object falls under the sole influence of gravity.

Drag Force

As an object falls through the air, it experiences an upward force called air resistance or drag force.
Drag force depends on the speed of the falling body, area of the body, density of the air, and drag coefficient.
Drag Force = 0.5 x d x v² x A x C

Terminal Velocity

Terminal velocity is the constant maximum velocity reached by a body falling through the atmosphere under gravity.
It occurs when the sum of the drag force and buoyancy equals the downward force of gravity acting on the object.

Work and Power

Work is any action or activity where force is applied, such as a weightlifter exerting force to hold a heavy load or a student solving physics problems.
Work is done only when a body is displaced under the application of force along the direction of force.

Work Done

Work done = Force x displacement x cosθ (W = Fxd x cosθ)
The amount of work done depends on the magnitude of the applied force, displacement of the body, and the angle between the displacement and force applied.
Unit of work done: SI unit is Joule, smaller unit is erg.

Example Problem

Pema pushes a box through a distance of 3m with a force of 100 N. The work done by Pema is calculated as: W = F x d = 100 x 3 = 300 J.

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Description

Quiz on the concept of falling objects, including the ideas of Aristotle, Galileo Galilei, and Isaac Newton on gravity and forces affecting falling objects. Understand the concept of weight and gravity.