A dog lies on the floor and refuses to move. When you pull the lead with a force

of 100 N and at an angle of 30 with the horizontal, the dog slides along the floor.

Determine the coefficient of friction, if the dog has a mass of 25 kg. (You can take

g = 10 m/s2.)

My working. $\displaystyle 100-F-250sin30=25a $

Surely I need to have been told the acceleraion to work out F.