I have 2 problems I have forgot how to do.(adsbygoogle = window.adsbygoogle || []).push({});

1. An Arrow is shot at an angle of 45 degrees abouve the horizontal at 69 m/s. (a) How high will the arrow go? (b) what horizontal distance will the arrow travel.

these are the equations I know:

Dx=Vxt

(Dx: verticle distance, Vx: Verticle Velocity, t: time)

Dy=Vyt+1/2at^2

(Dy: Horizontal Distance, Vy: Horizontal Velocity, t: time, a: acceleration)

Vx=VIcosø

(Vx: Verticle Velocit, VI: I dont know what this means but it could mean initial velocity)

Vy=VIsinø

As far as this question goes... I have no clue... I think I was absent when my teacher went over this... but my exams are tomorrow and I don't have enough time time to ask him about it... please help.

2. What is the Coefficient of Friction for a 2000 kg car that skids to a stop with an acceleration of -3m/s^2

these are the equations I know for this problem... this problem isn't that hard but there doesn't seem to be enough information. I need a pushing force!!

W=mg

(W:weight, M: mass, g: accel. due to gravity)

Fnet=ma

(Fnet: Net Force, a: acceleration)

Fnet=Fp+Ff

(Fp: pushing force, Ff: Frictional force)

Ff=µFn

(µ: coefficient of friction, Fn: Normal Force)

for this problem I know that the mass (2000 kg) and the acceleration (-3m/s^2) so Fnet=ma, Fnet= 2000*-3, Fnet=-6000.

I need to find Ff so I can solve for µ (Ff=µFn) cuz I already know Fn: W=mg, 2000*9.8, W=19600. and Fn=W when on a flat surface. so Fn=19600

to find Ff I'd use this equation: Fnet=Fp+Ff. I know Fnet=-6000 but I don't know Fp or Ff... Help

any help would be greatly apreciated!!

P.S. I already know the answers (1.) 121m and 484m (2.) .306. all I need to know is how to get those answers!!!

Thanks

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# Homework Help: Exam review: don't remember how to do this

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