Help on a rather simple physics question

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In summary, the conversation discusses the estimation of the terminal velocity and drag coefficient of a feather dropped from a height of 1.5m along with a steel ball of equal mass. The solutions involved using kinematic equations and considering the negligible drag on the steel ball. However, it was noted that the kinematic equations may not apply to the feather's motion due to air resistance. It was also mentioned that if the feather reaches its terminal velocity instantaneously, the distance fallen, time taken, and velocity can be calculated.
  • #1
Fullmetalx
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Homework Statement


Suppose you drop a feather and a steel ball of equal masses (0.014 kg) at the same time from a height of 1.5 m and you are told that the feather hits the floor 3.5 s after the steel ball. Estimate the value of the terminal velocity of the feather in air.

Estimate the feather's drag coefficient.


Homework Equations



v=mg/c

The Attempt at a Solution



I assumed the drag on the steel ball is negligible. So i used r=vit +.5at^2 to find the time it takes for it reach the ground. I then added 3.5s and used another kinematic equation to find the final velocity or terminal velocity. I then plugged the answer into the above equation to find c. it was wrong
 
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  • #2
What does the v-t graph of the feather look like?
i.e. do the kinematic equations even apply to it's motion?

Consider: if the air-resistance for the steel ball can be neglected - so it never reaches it's terminal velocity - then what is the case for the feather? How long does it take the feather to reach it's terminal velocity?
 
  • #3
Assume that the feather reaches its terminal velocity instantaneously. How far did it fall? How many seconds did it take to fall this distance? What was its velocity?
 

1. What is the difference between velocity and acceleration?

Velocity is a measurement of an object's speed and direction, while acceleration is a measurement of how quickly an object's velocity is changing over time. In other words, velocity tells us how fast and in which direction an object is moving, while acceleration tells us how quickly the object's velocity is changing.

2. How do I calculate force?

Force is calculated by multiplying an object's mass by its acceleration. This is represented by the equation F=ma, where F is force, m is mass, and a is acceleration.

3. What is the difference between static and kinetic friction?

Static friction refers to the force that must be overcome to set an object in motion, while kinetic friction is the force that resists the motion of an object that is already in motion. In other words, static friction prevents an object from moving, while kinetic friction slows down an object's motion.

4. How does Newton's first law of motion relate to inertia?

Newton's first law of motion states that an object at rest will stay at rest and an object in motion will stay in motion with a constant velocity, unless acted upon by an external force. This is directly related to inertia, which is an object's resistance to changes in its state of motion.

5. Can you explain the concept of work in physics?

In physics, work is defined as the product of the force applied to an object and the distance the object is moved in the direction of the force. This means that in order for work to be done, there must be a force applied to an object and the object must move in the same direction as the force.

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