Final answer:
The frictional force for the object is -40 Newtons.
Step-by-step explanation:
To determine the frictional force, we use the formula: frictional force = coefficient of friction × normal force. The normal force is given by the weight of the object, which is mass × gravitational acceleration (N = m × g). Here, mass (m) is 4 kg, and gravitational acceleration (g) is given as 10 m/s². So, the normal force is 4 kg × 10 m/s² = 40 N.
Now, applying the formula for frictional force: frictional force = coefficient of friction × normal force, we substitute the values. The coefficient of friction is 0.25, and the normal force is 40 N. Therefore, frictional force = 0.25 × 40 N = 10 N.
However, it's crucial to consider the direction of the force. The negative sign indicates that the frictional force acts opposite to the direction of motion, making the final answer -10 N.
Therefore, the frictional force for the object with a mass of 4 kg sliding on a surface with a coefficient of friction of 0.25 is -40 Newtons.