Solve Projectile Motion: Angle=20°, Height=20m

[dsptl]

A car is moving with constant velocity along a slope as shown in the figure. The magnitude of the velocity is 10m/s. Find the position of point A where the car hits the ground.

Angle = 20 degree
Height = 20m


http://maxupload.com


I have freaking no idea form where to start. Please help asap

 

[danago]

What is the initial velocity in the vertical and horizontal directions?

 

[dsptl]

i think

Vy = 10sin20degree

Vx = 10cos20degree

 

[danago]

Alright, now how can you determine how long before it hits the ground?

 

[dsptl]

Alright, now how can you determine how long before it hits the ground?

y = vi * t + .5at*t

20 = 3.4t - 5t*t

 

[danago]

y = vi * t + .5at*t

20 = 3.4t - 5t*t

You need to be careful of your signs. You have acceleration as negative there, but you have both displacement and velocity as positive, even though they are in the same direction as acceleration here. If you try to solve that you will get complex solutions.

 

[dsptl]

so is it like

-20 = -3.4t - 5t*t

 

[Dschumanji]

i think

Vy = 10sin20degree

Vx = 10cos20degree

Is the positive y direction in your coordinate system pointing downward?

 

[danago]

so is it like

-20 = -3.4t - 5t*t

Thats better.

 

[dsptl]

then I just multiply t by Vx to get the ans

thx a lot 4 the help