Recent content by EinsteinApple

If I define gravity as "+" in this example, then I can define friction as "+" too? Therefore, if I define gravity as "-", then friction has to be "-" because it's opposite to the movement? Now I am more confused

Homework Statement Projectile motion questions, Kinematics questions: my physics teacher defined acceleration due to gravity as -9.81 m/s2. Specifically in questions regarding: dropping an object, throwing an object downwards, obliquely launching an object. Today we are studying a box on...

I just assumed that y2 = 0 because it hits the ground. Therefore, I assumed because he was holding the slingshot y1 couldn't equal 0. Therefore if y1=0, then y2= a negative value because it's lower.

Homework Statement A man builds a slingshot that can launch water balloons. If he launches a water balloon at 45.0 degrees to the horizontal at a speed of 35.0 m/s, how far away will the balloon hit? Homework Equations xf=xi + vix t vfy=viy+at yf=yi + 1/2(viy+Vfy)t yf=yi + viyt + 1/2at^2...

I understand! I should solve for v1, then use a secondary equation to find t.

So for each movement I should ask myself: What is the segment of movement? In this case it's the rock out of a slingshot. Therefore v1 is unknown because it's already launched out of the slingshot. V2 = given Because I am having difficulties knowing if v1=0 or v2=0 or neither

I understand that's in an unknown, I just assumed I could assume. Especially since my only two available equations have v1 in them. d=v1+v2/2 x t 4=(unknown) + (5)/2 x t t = 1.6s (I know this is incorrect) v2=v1+at 5=unknown +(-9.81)t t = -0.51 s. (I know this is correct but wrong sign)

Thank you! To clarify: the motion I am interested in is the rock flying from the slingshot. Therefore can I assume that v1=0? Or no because v1 is the rock out of the slingshot and therefore it would be a positive value?

I believe it starts out of the sling at 5.0 m/s so that's v1. However it ends when it hits the branch? But it doesn't really, it will just bounce off and go in another direction.

Homework Statement Laura propels a stone straight up with her slingshot. The stone strikes a tree branch 4.0m above her. It strikes the branch with a velocity of 5.0m/s. How long does this take? a= -9.81 m/s2 v1 = 5.0m/s d= 4.0 m[/B] Homework Equations d=vit+1/2at2[/B] d=v1+v2/2 x t...