A sled is at rest on a horizontal field. The sled has a mass of 21.6kg. A man exerts a horizontal force of 49.7N on the sled. As soon as the sled starts to move, a friction force of 13.8N acts on the sled.
a. What is the acceleration of the sled while the man is pushing the sled?
b. What is the acceleration of the sled just after the man stops pushing it?
F = 49.7 - 13.8 = 21.6 a
so
a = (449.7-13.8)/21.6
F = -13.8
a = - 13.8/21.6
To find the acceleration of the sled, we need to apply Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
a. What is the acceleration of the sled while the man is pushing the sled?
To calculate the net force acting on the sled, we need to subtract the force of friction from the force exerted by the man.
Net force = Force exerted - Force of friction
Net force = 49.7 N - 13.8 N
Net force = 35.9 N
Now we can calculate the acceleration of the sled using Newton's second law:
Acceleration = Net force / mass
Acceleration = 35.9 N / 21.6 kg
Acceleration ≈ 1.66 m/s^2
Therefore, the sled has an acceleration of approximately 1.66 m/s^2 while the man is pushing it.
b. What is the acceleration of the sled just after the man stops pushing it?
Once the man stops pushing the sled, the only force acting on it is the force of friction. Therefore, the net force is equal to the force of friction.
Net force = Force of friction = 13.8 N
Again, we can use Newton's second law to find the acceleration of the sled:
Acceleration = Net force / mass
Acceleration = 13.8 N / 21.6 kg
Acceleration ≈ 0.64 m/s^2
Therefore, the sled has an acceleration of approximately 0.64 m/s^2 just after the man stops pushing it.