How Is Work and Kinetic Energy Calculated in Physics Problems?

Click For Summary
SUMMARY

This discussion focuses on calculating work and kinetic energy in physics problems, specifically using the work-energy principle. The key equations include the kinetic energy formula, KE = 1/2mv², and the work done by gravity, which is calculated as the product of mass, gravitational acceleration, and height. For example, the work done on a 2.5-kg book falling 3.0m is 73.5 J, while the minimum work required to lift a 150-kg block 2.0m is 2940 J. Participants also analyze kinetic energy for various scenarios, including a roller coaster and a paint chip in orbit.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with the concepts of potential and kinetic energy
  • Basic knowledge of gravitational force and acceleration (9.81 m/s²)
  • Ability to apply the kinetic energy formula, KE = 1/2mv²
NEXT STEPS
  • Study the work-energy theorem in detail
  • Learn how to calculate gravitational potential energy
  • Explore real-world applications of kinetic energy in roller coasters
  • Investigate the effects of mass and velocity on kinetic energy calculations
USEFUL FOR

Students studying physics, educators teaching mechanics, and anyone interested in understanding the principles of work and energy in physical systems.

Junebugg
Messages
1
Reaction score
0

Homework Statement



6. A 2.5-kg book slides horizontally and falls from a shelf 3.0m above the floor. How much work does the force of gravity do on the book as it falls 3.0m?
F. 1.2 J
G. 7.5 J
H. 24.5 J
J. 73.5 J

7. Which of the following is the minimum amount of work done by a hydraulic lift to raise a 150-kg aluminum block 2.0m vertically?
A. 75 J
B. 300 J
C. 1470 J
D. 2940 J

8. The motion of roller coasters depends upon the conversion of potential and kinetic energy. a 100-kg car starts from rest at the top of a hill with a height of 50 m. Which of the following is this car's kinetic energy at the bottom of the hill?
F. 150 J
G. 5000 J
H. 49,000 J
J. 98,000 J

9. A 0.25-g paint chip comes off a satellite orbiting Earth. The velocity of the paint chip is 7000 m/s. Which is the kinetic energy of the paint chip?
A. 1750 J
B. 6125 J
C. 12,250 J
D. 24,500 J

10. An automobile was moving at 15 m/s and accelerated at 2 m/s^2 for 2 s. Which was its final speed?
F. 17 M/S
G. 25 M/S
H. 27 M/S
J. 35 M/S

Homework Equations


ke=1/2mv^2



The Attempt at a Solution


for 8 I'm getting G or H
for 9 I'm getting A or B
for 10 I'm getting J
 
Physics news on Phys.org
Pls post your working.
 

Similar threads

Replies
1
Views
2K
Replies
6
Views
1K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 12 ·
Replies
12
Views
2K
Replies
12
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
12
Views
2K
Replies
17
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K