Calculating the corresponding percentage

  • Thread starter Thread starter adam640
  • Start date Start date
AI Thread Summary
To find the corresponding percentage fall in speed when the kinetic energy is 51% lower than the initial value, the relationship between kinetic energy and speed must be established. The initial kinetic energy (Ek1) is given by Ek1 = 1/2 mv^2, and the reduced kinetic energy (Ek2) is 49% of Ek1. By setting up the equation Ek2/Ek1 = 49/100, the relationship between the two speeds can be derived. This leads to the conclusion that the new speed is approximately 7% lower than the initial speed. The calculation demonstrates how changes in kinetic energy directly affect speed.
adam640
Messages
19
Reaction score
0

Homework Statement



A car is traveling at initial speed 5.5ms-1. The car is on a decline of 8o. The brakes are used and the car stops after traveling 10m along the road (with no skidding).

At the moment when kinetic energy is 51% lower than the initial value,
find the corresponding percentage fall in speed.


Homework Equations


Ek = 1/2mv2


The Attempt at a Solution


E is 51% lower, so \frac{2(0.49)Ek}{m}=v2
Clueless?!
 
Physics news on Phys.org
Start with

\frac{Ek_2}{Ek_1}=\frac{49}{100}

From that relationship, get a relationship between the two velocities.
 

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 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
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

Stopping distances on a downward slope
Replies
3
Views
2K
Finding kinetic energy consevered after collision
Replies
4
Views
2K
Calculating Separation of Cars in a Convoy Moving at Max Speed
Replies
4
Views
3K
Momentum and percent kinetic energy loss
Replies
3
Views
5K
Car Crash Analysis: Analyzing Friction & Speed
Replies
9
Views
4K
Motion problem: motorist's braking time including reaction time
Replies
1
Views
2K
Final velocity of a car rolling down a ramp using energy
Replies
1
Views
3K
How to calculate angular speed?
Replies
7
Views
2K
Calculating Stopping Distance for Car Traveling at 3.0v
Replies
1
Views
8K
Calculate power to have the car at a certain speed
Replies
4
Views
2K

Hot Threads

Recent Insights

Back
Top