Calculating Kinetic Energy: Understanding the Equation and Common Errors

AI Thread Summary
The discussion centers on calculating the kinetic energy of a 3kg object with a velocity of < 6i -1j > m/s. The calculated kinetic energy is 55.5 J, while the book states it as 60 J, leading to confusion. Participants agree that the discrepancy likely arises from rounding practices and significant figures, noting that the velocity has only one significant figure. The consensus is that the book's answer is a rounded figure to maintain consistency with significant figures. This highlights the importance of understanding rounding in physics calculations.
m2009aquario
Messages
2
Reaction score
0
kinetic energy, help!?

A 3kg object has a velocity < 6i -1j > m/s. What is its kinetic energy at this moment? According to the book I'm using the ans is 60J but I get 55.5 J...What em I doing wrong?
 
Physics news on Phys.org


They probably just rounded their answer. If you use sig figs, there's only one sig fig in < 6i -1j >, so they rounded 55.5 to 60 to conserve sig figs.
 


i'm getting the same answer as you
 


Hey thanks guys, I was really going nuts here trying to figure it out, it only made sense that the answer was rounded.
 

Thread 'Rolling without slipping on a curved surface'

Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
View full post »
Thread 'Voltmeter readings for this circuit with switches'

Thread 'Voltmeter readings for this circuit with switches'

TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
View full post »

Similar threads

Potential and Kinetic energy equations including drag coefficient
Replies
1
Views
1K
Work done during a collision -- Change in Kinetic Energy & change in Momentum
Replies
1
Views
2K
Confused about a conservation of energy problem
Replies
4
Views
2K
Minimal rotational kinetic energy for a gyroscope to precess
Replies
33
Views
3K
Conservation of Energy with Gravitational Potential Energy
Replies
6
Views
2K
Energy of particle in simple harmonic motion
Replies
13
Views
1K
What's the source of increase in rotational energy of carousel?
Replies
9
Views
2K
Kinetic energy and momentum in an elastic collision
Replies
22
Views
4K
Total energy of a mass hanging on a spring
Replies
12
Views
3K
Using Orbital Energy to Calculate Velocity
Replies
3
Views
1K

Hot Threads

Recent Insights

Back
Top