Forces on a ball in a moving car

1. Oct 20, 2008

theneedtoknow

1. The problem statement, all variables and given/known data

a) A 1 kg ball hands from a 1m rope in a car accelerating at 5 m/s^2, Does the ball have an acceleration?if so what are the magnitude and direction of the balls acceleration

b) suppose the ball makes a 10 degree angle witht he vertical. If possible determine the truck's velocity, if possible determine the truck's acceleration.

2. Relevant equations

F=ma? lol

3. The attempt at a solution

a) Ok so i assume the ball would have an acceleration but how do i fugre it out? I know gravity acts on it and the tension of the rope acts on it...and i assume if the car is accelerating then the ball will swing backwards and settle in a position where the rope is slanting towards the back side of the car... but how do i actually calculate them? do i break down the forces in the x and y components? would then the y component be gravity straight down or gravity along the angle at which the rope is bent or what?

b) Well i know we cant determine velocity at least, but we should be able to determine the acceleration...but how?

if it makes a 10 degree angle to the vertical...then the force of tension on the rope would be t = mg / cos(10 degrees) (is this right)? I really have no idea how to do either part, can i get a hint of where to start

2. Oct 20, 2008

Redbelly98

Staff Emeritus
(a) What is the ball's motion relative to the car?

(Hint: the answer is simpler than you might think.)