An unknown force pushes a 17 kilogram block across a smooth (frictionless) floor. three seconds after the force is first applied to the block, the block is moving with a speed of 6 meters per second. what is the magnitude of the unknown force?

By definition we know that Force is equal to mass by acceleration F = m * a. Also, by definition acceleration equals velocity between time a = v / t. Therefore, the expression for the force will be given by: F = m * (v / t). Substituting the values: F = 17 * (6/3) = 34N. The force is 34N