Finding Mass: Calculating Friction & Motion

AI Thread Summary
To determine when the copper block will start to slip on the steel turntable, the problem involves calculating forces using Newton's second law and the coefficient of static friction. The normal force is equal to the weight of the block, which is expressed as N = mg. The frictional force can be calculated using Ff = μN, where μ is the coefficient of static friction (0.53). However, without knowing the mass of the block, it is impossible to calculate the exact time interval for slipping to occur. The discussion emphasizes the need to find the mass to solve the problem accurately.
chenny
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A copper block rests 30.cm from the center of a steel turntable. The coefficient of static friction between the block and the surface is .53. The turntable starts from rest and rotates with a constant angular acceleration of .50 rad/s^2. After what time interval will the block start to slip on the turntable.
Hint: The normal force in this case equals the weight of the block.



Fc=u(mew)timesN



Tangential Speed = .15m/s
mew =.53
N = mg
N = m(9.81 m/s^2)

How do I find the mass?


Please and Thank you...
 
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Hi chenny,

This is a rotational motion problem. By Newton's 2nd law, Net force= ma. F- Ff = ma. Since tangential acceleration = radius x angular acceleration, F- Ff = m (0.3m x 0.5 rad/s²). When block starts to slip, Ff = (meu)N = 0.53mg. Manipulate Newton's 2nd law, u get F = ma = m dv/dt and solve for t. But u cannot find the mass of the block, thus u cannot find the time when block starts to slip on turntable.

How to find the mass of the block?? Can someone pls help us??
 

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