Grade 11 physics
posted by John on .
a string can hold up 12 kg without breaking. You tie the string to a 30kg object sitting on ice and use it to pull the object horizontally 22m. Calculate the minimum possible time to complete the task

Assume friction on ice is zero. All the force goes for acceleration.
Minimum possible time t is such that
22 m = (a/2)*t^2 with maximum possible a
Maximum accelaration a is
a = Fmax/m = (12*9.8 N)/30 kg
= 3.92 m/s^2
Now solve for t in the first equation, using that a value. 
3.35