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# Nabs

• ### Physics problem - electrostatic unit?

I've tried solving this question with three different methods but I'm stuck with which one is correct... Please help!

Here is the question, I attached a diagram below:

A 30cm string has a 5 gram pith ball attached to each end. The string is hung over a meter stick and due to an electrostatic repulsion, the string makes an angle of 28 degrees where it is hanging. Assuming the charge on each pith ball is the same, determine the charge of the pith ball.

• ### Another Physics Problem!?

This question is from the forces unit:

A 50 kg crate is resting on the floor. the coefficient of friction between the floor and the crate is 0.5. a rope is attached to the crate is being pulled at an angle 25 above the horizontal. what is the largest force that can be applied to the rope that will allow the crate to stay at rest?

• ### Physics Problem!!?

The question deals with two stage motion:

You are driving at 80km/h when you notice a person step out into the road. You need 0.43s to react and start braking. After that, you brake with an acceleration of -4.2m/s². Determine you total stopping distance.