A sled of mass 51 kg is pulled along snow-covered, flat ground. The static friction coefficient is 0.30, and the sliding friction coefficient is 0.10.
(a) What does the sled weigh?
(b) What force will be needed to start the sled moving?
(c) What force is needed to keep the sled moving at a constant velocity?
(d) Once moving, what total force must be applied to the sled to accelerate it 4.4 m/s2?
To answer these questions, we need to understand the basic concepts of friction and forces. Let's go through each question step by step and explain how to find the answers.
(a) What does the sled weigh?
The weight of an object can be calculated using the formula:
Weight = mass x acceleration due to gravity
In this case, the mass of the sled is given as 51 kg. The acceleration due to gravity is approximately 9.8 m/s^2. Therefore,
Weight = 51 kg x 9.8 m/s^2
Calculating this will give us the weight of the sled.
(b) What force will be needed to start the sled moving?
To start the sled moving, we need to overcome static friction. The force required to overcome static friction can be calculated using the formula:
Force = static friction coefficient x weight
The given static friction coefficient is 0.30, which we calculated the weight in the previous step. Plug in these values into the formula to find the force required to start the sled moving.
(c) What force is needed to keep the sled moving at a constant velocity?
Once the sled is in motion, we need to overcome sliding friction to keep it moving at a constant velocity. Sliding friction is usually less than static friction. The force required to overcome sliding friction can be calculated using the formula:
Force = sliding friction coefficient x weight
The given sliding friction coefficient is 0.10, and we already calculated the weight of the sled. Plug in these values into the formula to find the force required to keep the sled moving at a constant velocity.
(d) Once moving, what total force must be applied to the sled to accelerate it 4.4 m/s^2?
To accelerate an object, we need to apply a net force larger than the force of friction. In this case, we need to overcome both static and sliding friction to accelerate the sled.
The total force required to accelerate the sled can be calculated using the formula:
Total force = mass x acceleration + force of sliding friction
In this case, the mass of the sled is given as 51 kg, and the desired acceleration is 4.4 m/s^2. We already calculated the force of sliding friction in a previous step. Plug in these values into the formula to find the total force required to accelerate the sled.