The man pushes with a force of 200 N. The child and sled combo has a mass of 30 kg and the coefficient of static friction is 0.15. Find the friction force
First, we need to calculate the weight of the child and sled combo:
weight = mass x gravity
weight = 30 kg x 9.8 m/s^2
weight = 294 N
Next, we can use the coefficient of friction to calculate the maximum static friction force:
friction force (max) = coefficient of static friction x weight
friction force (max) = 0.15 x 294 N
friction force (max) = 44.1 N
Since the man is pushing with a force greater than the maximum static friction force, the sled will start to move. The friction force at this point will be equal to the kinetic friction force, which can be calculated using the coefficient of kinetic friction:
coefficient of kinetic friction = 0.10 (assumed)
friction force (kinetic) = coefficient of kinetic friction x weight
friction force (kinetic) = 0.10 x 294 N
friction force (kinetic) = 29.4 N
Therefore, the friction force when the sled is moving will be 29.4 N.