Find the kinetic energy

In summary, the question is asking to find the kinetic energy of a ton of water moving at 60 min/hr expressed as (ft)(lbf). However, the answer provided in the booklet is incorrect. After calculating the kinetic energy using the given formula and values, it seems that the velocity of 60 min/hr may be a typo and should possibly be 60 miles/hr. This gives a correct answer of 240838 (ft) (lbf).
  • #1
serven7
3
0
This question is directly from David M. Himmelblau and James B. Riggs Basic Principles and Calculations in Chemical Engineering, 7th Edition cd rom workbook part1 unsolved problem q1.3. I am reworking through the basics, However when i went through this question I couldn't figure out the velocity.

Find the kinetic energy of a ton of water moving at 60 min/hr expressed as (ft)(lbf).?

Answer from booklet= 2.40*10^5 (ft) (lbf). However i can't find the velocity of the moving water i tried using gc and converting mass to slug*ft/s^2 or lbm x ft/s^2. please help!
 
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  • #2
welcome to pf!

hi serven7! welcome to pf! :smile:

(try using the X2 tag just above the Reply box :wink:)
serven7 said:
Find the kinetic energy of a ton of water moving at 60 min/hr expressed as (ft)(lbf).?

erm :redface:everything moves at 60 min/hr ! :biggrin:

show us your full calculations, and then we'll see what went wrong, and we'll know how to help! :smile:
 
  • #3
Find the kinetic energy of a ton of water moving at 60 min/hr expressed as (ft)(lbf).?
no velocity is listed

a ton=2000 pound mass
1hr =3600seconds(1.) 2000/32.174 = 62.2 slug mass

(2) 1 lbf = 1 slug*ft/s2 so... slug mass* gc(32.2ft/s2)

(3) so KE = 0.5* slug* (ft/s2)2 ,hence 0.5*62.2slug*(32.2ft/s2)2 = 32246 (ft) (lbf)

Answer from booklet= 2.40*105 (ft) (lbf).. answer is wrong.
Don't know what am doing wrong, question does not provide velocity.
 
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  • #4
I think 60 min/hr is a typo for 60 miles/hr.

At least, that velocity gives me the "right answer".
 
  • #5
Thx, the question was doing my head in cux such a simple question and am spending so much time on it.

KE= 0.5*62.2slug*(88ft/s2)2 =240838(ft) (lbf)
 
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1. What is kinetic energy?

Kinetic energy is the energy an object possesses due to its motion. It is a form of energy that depends on an object's mass and velocity.

2. How do you calculate kinetic energy?

The formula for calculating kinetic energy is KE = 1/2 * m * v^2, where m is the mass of the object and v is its velocity.

3. What are the units of kinetic energy?

The units of kinetic energy are Joules (J) in the International System of Units (SI). In some older systems, it may be measured in foot-pounds (ft-lbf) or kilogram-meters squared per second squared (kg-m^2/s^2).

4. What factors affect an object's kinetic energy?

An object's kinetic energy is affected by its mass and velocity. The greater the mass and velocity of an object, the greater its kinetic energy will be.

5. How is kinetic energy applied in real-world scenarios?

Kinetic energy is applied in many real-world scenarios, such as in transportation (e.g. cars, planes, trains), sports (e.g. throwing a ball, running), and in the production of electricity (e.g. hydroelectric dams, wind turbines). It is also important in understanding the behavior of particles in physics and chemistry.

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