Highland Games Hay Toss: Solving for Time and Direction in 2D Kinematics

[matt@USA]

2D Kinematic Equation! Need Help! I have a test tomorrow!

Homework Statement

One of the most popular events at highland games is the hay toss, where competitors use a pitchfork to throw a bale of hay over a raised bar. Suppose the initial velocity of a bale of hay is varrowbold = (1.32 m/s)xhatbold + (8.85 m/s)yhatbold.
(a) After what minimum time is its speed equal to 7 m/s?

(b) How long after the hay is tossed is it moving in a direction that is 45.0° below the horizontal?

Homework Equations

I figured out the answer to part A using the quadriatic equation by saying that ...
t=2Vnotyg+-sqrt of (-2Vnotyg)^2 - 4(g^2)(Vnotx^2+Vnoty^2-V^2)/2(g^2).
I came up with the right answer of .201s.

I am stuck with part B. I don't know if I am overanalizing it or what. Someone please help!

 

[PeterO]

Homework Statement

One of the most popular events at highland games is the hay toss, where competitors use a pitchfork to throw a bale of hay over a raised bar. Suppose the initial velocity of a bale of hay is varrowbold = (1.32 m/s)xhatbold + (8.85 m/s)yhatbold.
(a) After what minimum time is its speed equal to 7 m/s?

(b) How long after the hay is tossed is it moving in a direction that is 45.0° below the horizontal?

Homework Equations

I figured out the answer to part A using the quadriatic equation by saying that ...
t=2Vnotyg+-sqrt of (-2Vnotyg)^2 - 4(g^2)(Vnotx^2+Vnoty^2-V^2)/2(g^2).
I came up with the right answer of .201s.

I am stuck with part B. I don't know if I am overanalizing it or what. Someone please help!

When it is moving at 45 degrees, the verticla (y) and horizontal (x) component are the same size.
At 45 degrees down means the y-component is 1.32 down.

 

[matt@USA]

So I would say 1.32sin45, which would equal what? I am confused ... My mind is scrambled right now.

 

[PeterO]

So I would say 1.32sin45, which would equal what? I am confused ... My mind is scrambled right now.

The original velocities given didn't have a sin45 component, so why did you put one in.

Hint: at what time will the hay bale have a vertical component of 5 m/s down? If you can work that out, you can solve part (b) in a similar way

 

[matt@USA]

So I would use the Vy=Voy+Ayt right? And since Voy=0, the equation would be t=Vy/Ay?

 

[matt@USA]

Nm, I got it! It was t=x+y/g! I am over analizing this stuff way too much!