According to newtons first law of motion, what is required to make an object slow down?

It is necessary to determine the specific heat of an unknown object. the mass of the object is 201.0g it is determined experimentally that it takes 15j to raise the temperature 10°c. what is the specific heat of the object? 3,020,000 j/kg ∙ k 1500 j/kg ∙ k 0.00130 j/kg ∙ k 7.46 j/kg ∙ k