Don't get mechanics!!! (1 Viewer)

[NizDiz]

Can someone please help me!, I just started mechanics at school and I don't even get the basics of it. With angular velocity, is there an equation or some way to derive it and get there, if so, can someone please share on here to do that. Theses are basic questions but I have no idea if I'm doing it right.

1. A particle is traveling in uniform circular motion 5m from centre O, The particle travels 30m after 6 seconds.

(a) Find the angular displacement of the particle
(b)Hence, find the angular velocity
(c) Find its horizontal and vertical displacement from O correct to 2 decimal places

2. A ball of mass 0.5 kg is rotated at the end of an inelastic string of length 2m in a horizontal circle at 5 m/s.

(a) Find the angular velocity.

Also, how do you show the normal acceleration is equal to rw^2

All help would be greatly appreciated. Thanks guys

 

[Carrotsticks]

Firstly, do you understand the concept of 'resolving' or 'balancing' forces? Forming the fundamental equations of motion, by resolving forces, is essential to Mechanics.

 

[NizDiz]

yeh, how do u do these basic questions though?, once that's done, i can understand angular velocity and whole other basic stuff with it all

 

[braintic]

Can someone please help me!, I just started mechanics at school and I don't even get the basics of it. With angular velocity, is there an equation or some way to derive it and get there, if so, can someone please share on here to do that. Theses are basic questions but I have no idea if I'm doing it right.

1. A particle is traveling in uniform circular motion 5m from centre O, The particle travels 30m after 6 seconds.

(a) Find the angular displacement of the particle
(b)Hence, find the angular velocity
(c) Find its horizontal and vertical displacement from O correct to 2 decimal places

2. A ball of mass 0.5 kg is rotated at the end of an inelastic string of length 2m in a horizontal circle at 5 m/s.

(a) Find the angular velocity.

Also, how do you show the normal acceleration is equal to rw^2

All help would be greatly appreciated. Thanks guys

1a 30m is the arc length. Just use l=rθ to find θ
1b divide θ radians by 6 seconds to get an angular velocity in radians per second
1c The question is meaningless. Is it a vertical or horizontal circle? If horizontal, the vertical displacement from O is zero and the horizontal displacement from O is 5m (the radius). If vertical, there is no information to determine where in its orbit the particle is located.
2a Use v=rω where v=5 and r=2 to find ω (the angular velocity)

The correct term is centripetal acceleration. Even though this acceleration is perpendicular to the direction of motion, 'normal' is usually reserved for contact forces. Here the acceleration is caused by the tension in the string, not a contact force. The proof for the centripetal acceleration formula should have been given by your teacher. But you are allowed to just quote it in a question like this.

 

[NizDiz]

Thanks braintic!!, you're a legend