circular motion

A small fluffy toy hangs on a string in the rear window of a car. The car rounds a bend at 30ms-1 and the string hangs 20 degrees from the vertical.

There is a diagram just of the string hanging 20 degrees from vertical.


b) Calculate the radius of the curve in the road.
sin 20=mv^2/r
cos 20=mg
i dont know where the sin and cos came otherwise i know how to do this question sry i always get mixed up when to use cos and sin

Have you drawn a force diagram? I'm assuming you need to calculate the forces perpendicular to the string and make the centripetal and gravitational components equal.

Have you drawn a force diagram? I'm assuming you need to calculate the forces perpendicular to the string and make the centripetal and gravitational components equal.

yeah tension upwards and mg down

The tension in the string (it's horizontal component) is providing the centripetal force.
The vertical component of the tension balances the weight of the toy.

It's these two components that the sin and cos come from.

You should have Tsin theta and Tcos theta in those equations.

Ty i got it but im confused still in when to use sin or cos