Force of Friction

An Object with mass m and initial velocity v is brought to rest by a constant force F acting for a time t and through a distance d. Possible expressions for the magnitude of the force F are: i. $\frac{mv^2}{2d}$ ii. $\frac{2md}{t^2}$ iii. $\frac{mv}{t}$

ii only

iii only

i and ii only

ii and iii only

i, ii, and iii

A toy car of mass 6 kg moving in a straight path, experiences a net force given by the function F = -3t. At time t=0, the car has a velocity of 4 m/s in the positive direction and is located +8 m from the origin. The car will come instantaneously to rest at time t equal to

2/3 s

sqrt( 4/3 ) s

sqrt( 8/3 ) s

sqrt( 8) s

4 s

Determine the acceleration and the value of the normal force. Draw a free body diagram.

M = 10kg, $\theta$ = 30 degrees

A block of mass M = 5kg is placed on an incline of $\theta$ = 30 degrees. There is a frictional force of 15 N opposing the movement of the block. Determine the acceleration of the block. Draw a free body diagram to help find the answer.