Conservation of mechanical energy of ball of mass

AI Thread Summary
A ball with a mass of 240 g is initially moving at 20.0 m/s and has a gravitational potential energy of 70 J. When the ball reaches the ground, its potential energy becomes zero, and all energy converts to kinetic energy. The total mechanical energy, which is conserved, includes both potential and kinetic energy. By calculating the initial total energy and equating it to the final kinetic energy at ground level, the ball's impact speed is determined to be approximately 24.15 m/s. Understanding the conservation of mechanical energy is crucial for solving this problem.
checkmarks
Messages
12
Reaction score
0

Homework Statement


A ball of mass 240 g is moving through the air at 20.0m/s with a gravitational potential energy of 70J. With what speed will the ball hit the ground?

Homework Equations


Eg = mgh
Ek = 1/2mv^2
W = mgd

The Attempt at a Solution


this is what i did:
at 0m, potential energy is 0 so kinetic energy must have 70J now.

Ek = 1/2mv^2
70 J = 1/2(0.24kg)v^2
v = 24.15 m/s

I don't know what to do with the 20 m/s that was given and yeah...please help!
 
Physics news on Phys.org
The potential and kinetic energy that it had initially is now all kinetic by the time it reaches the ground.
 
you have

potential energy + kinetic energy = total energy = constant

What is the total energy whe the ball is moving through the air? it's not 70 J.

At a height of 0 m, potential energy is indeed 0, so all the energy must be kinetic.
 
since he total mechanical energy is conserved equate the initial total mechanical energy
(pe+ke)to the final toal mechanical enrgy.
remeber pe=mgh ,so what is pe at ground level?
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Hooke's Law using Potential Energy
Replies
21
Views
1K
Potential and Kinetic energy equations including drag coefficient
Replies
1
Views
1K
What speed will the ball hit the ground?
Replies
2
Views
5K
Conservation of Energy when lifting a box up off the floor
Replies
5
Views
2K
Conservation of energy problem: Ball rolling down inclined plane and then through a loop-the-loop
Replies
10
Views
2K
Energy conservation equation to find equation for final velocity
Replies
4
Views
1K
Question on a ball dropping( conservation of energy)
Replies
1
Views
3K
Speed of charged balls after collision
Replies
13
Views
1K
Conservation of Energy with heat
Replies
5
Views
2K
How to calculate rebound speed of ball hitting a wall?
Replies
4
Views
5K

Hot Threads

Recent Insights

Back
Top