Question concerning initial velocity

AI Thread Summary
An athlete's long jump problem involves calculating the take-off speed given a jump angle of 31.6° and a distance of 7.78 m. The initial formula derived for distance appears incorrect, as the correct equation should involve the square of the initial velocity. The discussion highlights the importance of separating vertical and horizontal components to find the total time and then using that to calculate distance. Acknowledgment of algebraic mistakes is noted, emphasizing the need for careful organization in problem-solving. The conversation concludes with a reminder that simple errors can lead to incorrect results.
Casimi
Messages
11
Reaction score
0

Homework Statement



An athlete executing a long jump leaves the ground at a 31.6° angle and travels 7.78 m. What was the take-off speed?

I have tried to solve this question but somehow keep arriving at the wrong answer. The formula that I derived is :

distance=V(initial)*sin^2(theta)/g

Where am I going wrong here? Any help would be appreciated.
 
Physics news on Phys.org
Are you computing

distance=V0sin2θ/g

OR

Distance = V02sin2θ/g?

The second one is the one should use.
 
It seems as if I derived the wrong formula via a mistake in my algebra.

Thank you so much!
 
i get a different formula for it.

First take the vertical component, and find the total time taken. Now take the horizontal component of the velocity and multiply by time to find the expression for distance(range)

Substitute and get your answerEDIT: rock.freak answered first, i guess...
 
It seems like I should take more time to organize my thoughts and perform my algebra correctly. Simple mistakes are always my downfall!
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Initial velocity given time and angle
Replies
8
Views
2K
Find Initial Velocity Given Height, Range, and Initial Angle
Replies
4
Views
2K
Calculate initial speed of an athlete - projectile motion
Replies
15
Views
3K
Find the Initial Velocity and Launch Angle for a Particular Trajectory
Replies
10
Views
4K
Calculating the Force of a Jump on the Moon
Replies
10
Views
3K
Solved problem: Projectile in slanting tunnel
Replies
6
Views
1K
Find the initial velocity of the package relative to the ground
Replies
18
Views
2K
Finding the horizontal range without initial velocity
Replies
2
Views
3K
Projectile motion - determining initial velocity and angle
Replies
8
Views
2K
Initial velocity of ball B hit a free falling ball A
Replies
7
Views
2K

Hot Threads

Recent Insights

Back
Top