Finding velocity using given angle

[dahano]

Homework Statement

:
A body is projected with 50m/sec at an angle of 53 degree with the horizontal. After what time velocity makes an angle 33.7 degree with horizontal. (tan 33.7 = 2/3)[/B]

Homework Equations

: Mostly from 2-Dimension and maybe calculus.[/B]

The Attempt at a Solution

: I've first picked up the second part of the question and tried to find out the height at 33.7 degree angle by using h = uSinθt - 1/2gt but in this, I can't decide that what u should I put because 50m/sec is at the ground level. Moreover, I also don't know the time, t. And thus this method can not be used. What could be the other way? Please guide me in layman's term.[/B]

 

[yango_17]

Take into consideration that the motion consists of both x and y components (x=vcosθ and y=vsinθ). Perhaps you could try calculating what the initial speed and final speeds are for the y component. Then try calculating how much time it would take for that change in speed using your other kinematics formulas.

 

[dahano]

Take into consideration that the motion consists of both x and y components (x=vcosθ and y=vsinθ). Perhaps you could try calculating what the initial speed and final speeds are for the y component. Then try calculating how much time it would take for that change in speed using your other kinematics formulas.

Yep, that worked! I've got 2 seconds as the answer and hopefully it must be correct. Thanks :-)

 

[haruspex]

Yep, that worked! I've got 2 seconds as the answer and hopefully it must be correct. Thanks :-)

I confirm 2 sec. (More precisely, 2.03, using 9.8 for g.)