How Does the Speedometer Reading Change as an Object Falls?

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In summary, the conversation discussed the relationship between speed, acceleration, and time in free fall. It was mentioned that the acceleration of gravity, g, is 9.8m/s^2 and this means that the velocity increases by 9.8m/s every second. The kinematic equations of motion for free fall were also brought up, with the reminder that they only apply when the initial velocity is zero. The question of how to calculate the velocity change each second was raised, and it was clarified that the change in velocity is equal to gt. The conversation ended with the understanding that the acceleration of gravity means that the velocity increases by 9.8m/s every second.
  • #1
missie
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Let's say a rock had a speedometer on it so that you could measure how fast it was going at any moment. By how much would the speed reading on the speedometer increase with each second that it fell?

what is your answer to this question?

can you explain?

i also learned today that g = 9.8 for most things right?
 
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  • #2


missie said:
Let's say a rock had a speedometer on it so that you could measure how fast it was going at any moment. By how much would the speed reading on the speedometer increase with each second that it fell?

what is your answer to this question?

can you explain?

i also learned today that g = 9.8 [tex]m/sec^2[/tex] for most things right?
g, the acceleration of gravity, applies at or near the Earth's surface, for all objects. What did you learn about the relationship between speed, acceleration, and time?
 
  • #3


that no matter what time or how long it stays at g = 9.8 m/s
 
  • #4


missie said:
that no matter what time or how long it stays at g = 9.8 m/s
What I mean is, I know you have studied the kinematic equations of motion for free fall, you know, the ones like vf = vo + ?
 
  • #5


vf = vo + at ? and the teacher said for free fall it's vf = gt
 
  • #6


missie said:
vf = vo + at ? and the teacher said for free fall it's vf = gt
well, that's if vo is zero (if it starts from rest). In general, vf=vo +gt, or rearranging, vf-vo =gt, that is , [tex]\Delta v = gt[/tex]. So what's the velocity change each second? Don't forget units.
 
  • #7


how will i know the velocity change every second when i can't solve that because it doesn't tell time. It tells me to answer with words and that its not a math problem.
 
  • #8


Think about what is actually happening. When we say that g = 9.8 m/s^2 , what is that saying? Acceleration refers to the change in velocity over time.

An object in free fall starting from an initial speed of zero falls at a velocity of 9.8 m/s after ONE second. How fast do you think it's going after two seconds?
 
  • #9


should it be 9.8 x 2 = 19.6m/s at 2 second?
 
  • #10


You're one the right track yes.

What the acceleration 9.8m/s^2 means is that every second, the velocity increases by 9.8m/s. Now do you understand how that works?
 
  • #11


yes i understand now thank you so much ;]
 
  • #12


No problem :)
 

FAQ: How Does the Speedometer Reading Change as an Object Falls?

How does a speedometer work?

A speedometer is a device that measures the speed of a moving object. It works by using a small magnet attached to a rotating shaft, which turns as the wheels of the vehicle turn. This causes a metal cup to rotate, which is connected to a needle on the speedometer dial. The faster the wheels turn, the faster the magnet rotates and the higher the speed displayed on the speedometer.

Why does my speedometer show a different speed than my GPS?

There are a few reasons why your speedometer and GPS may show different speeds. First, speedometers are calibrated to show a higher speed to account for tire wear and other factors. Additionally, GPS devices may have a slight delay in updating the speed readings. Lastly, GPS measures your speed based on your movement in a straight line, while a speedometer measures the rotation of your wheels, which may be affected by curves and turns.

Can a speedometer show incorrect readings?

Yes, a speedometer can show incorrect readings for a variety of reasons. The most common cause is a faulty speed sensor, which can result in the needle sticking, jumping, or showing a consistently incorrect speed. Additionally, if the tire size on a vehicle has been changed, the speedometer may need to be recalibrated to accurately reflect the new tire size.

Does a speedometer work differently for different types of vehicles?

While the basic function of a speedometer remains the same for all vehicles, the design and calibration may vary slightly depending on the type of vehicle. For example, a speedometer on a bike may work differently than one on a car or motorcycle, as the size and rotation of the wheels are different.

What is the maximum speed a speedometer can show?

The maximum speed that a speedometer can show depends on the design and calibration of the device. Generally, most speedometers are designed to show speeds up to 120-160 mph, as this is the maximum speed limit in most countries. However, some specialty vehicles, such as race cars, may have speedometers that can show higher speeds.

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