Final answer:
The force needed to accelerate the sled on a horizontal surface is 107.8 N, which can be calculated by multiplying the coefficient of friction by the normal force.
Step-by-step explanation:
To calculate the force needed to accelerate the sled on a horizontal surface, we need to consider the force of friction. The force of friction can be found by multiplying the coefficient of friction (0.2) by the normal force. On a horizontal surface, the normal force is equal to the weight of the sled, which can be found by multiplying the mass (55 kg) by the acceleration due to gravity (9.8 m/s²). So, the normal force is 539 N (55 kg * 9.8 m/s²).
The force of friction is then 0.2 * 539 N = 107.8 N. Since the force of friction opposes the motion, the force needed to accelerate the sled is equal to the force of friction. Therefore, the force needed to accelerate the sled is 107.8 N.