Suppose a 47-N sled is resting on packed snow. The coefficient of kinetic friction is 0.14. If a person weighing 670 N sits on the sled, what force is needed to pull the sled across the snow at constant speed?
To find the force needed to pull the sled across the snow at a constant speed, we need to consider the net force acting on the sled. The net force is equal to the force of friction opposing the motion.
1. Start by calculating the force of friction using the equation:
frictional force = coefficient of kinetic friction * normal force
The normal force is equal to the weight of the sled plus the weight of the person, since both are acting downward:
normal force = weight of sled + weight of person
normal force = 47 N + 670 N
normal force = 717 N
frictional force = 0.14 * 717 N
frictional force = 100.38 N
2. Since the sled is moving at a constant speed, the force of friction is equal to the force applied to pull the sled. Therefore, the force needed to pull the sled is 100.38 N.
To find the force needed to pull the sled across the snow at a constant speed, we need to take into account the forces acting on the sled.
First, let's consider the force of friction. The force of friction can be calculated using the formula:
Frictional force = coefficient of friction * normal force
The normal force is the force exerted by the surface perpendicular to the sled. In this case, the normal force is equal to the weight of the sled and the person sitting on it, which is the sum of their weights:
Normal force = weight of sled + weight of person
Next, we need to calculate the weight of the sled and the person:
Weight = mass * acceleration due to gravity
Given that the sled weighs 47 N and the person weighs 670 N, we can calculate their masses:
Mass of sled = weight of sled / acceleration due to gravity
Mass of person = weight of person / acceleration due to gravity
Once we have the masses, we can find the normal force:
Normal force = weight of sled + weight of person
Now, we can calculate the force of friction:
Frictional force = coefficient of kinetic friction * normal force
Finally, the force needed to pull the sled at a constant speed is equal to the force of friction.