A 25 kg box is being pulled across a surface. The coefficient of kinetic friction between the box and the surface is 0.55.
a) if the box is moving at a constant speed, what is the pulling force?
b)If the pulling force is 350 N, what is the NET force acting on the box?
c)If the pulling force is 350 N, what is the acceleration of the box?
This is from a forces test working with newton's second law. Need the steps to figure it out.
M*g = 25kg * 9.8N./kg = 245 N. = Wt. of
the box = Normal force.
Fk = u*Fn = 0.55 * 245 = 134.75 N. = Force of kinetic friction.
a. Fp-Fk = M*a
Fp - 134.75 = M*0 = 0
Fp = 134.75 N. = Pulling force.
b. F(net) = Fp-Fk = 350 - 134.75 = 215.3
N.
c. a = (Fp-Fk)/M = 215.3/25 = 8.61 m/s^2
To answer these questions, we'll need to apply Newton's second law of motion, which states that the net force acting on an object is equal to the mass of the object multiplied by its acceleration. In this case, the net force is the sum of the force pulling the box and the force of friction acting against the motion of the box.
a) To find the pulling force when the box is moving at a constant speed, we need to know that the force of friction is equal and opposite to the pulling force. So, we can calculate the force of friction using the equation:
force of friction = coefficient of kinetic friction × normal force
The normal force is the force exerted on the box by the surface, which is equal to the weight of the box since the box is not in contact with any other surfaces. We can calculate the normal force using the formula:
normal force = mass × acceleration due to gravity
Substituting the given values:
normal force = 25 kg × 9.8 m/s^2 (acceleration due to gravity) = 245 N
Now, the force of friction can be calculated:
force of friction = 0.55 (coefficient of kinetic friction) × 245 N (normal force) = 134.75 N
Since the box is moving at a constant speed, the pulling force must be equal and opposite to the force of friction. Therefore, the pulling force is also 134.75 N.
b) The net force acting on the box can be calculated by subtracting the force of friction from the pulling force:
net force = pulling force - force of friction = 350 N - 134.75 N = 215.25 N
Therefore, the net force acting on the box is 215.25 N.
c) To calculate the acceleration of the box, we use the formula:
net force = mass × acceleration
Thus, the acceleration can be calculated by rearranging the formula as follows:
acceleration = net force / mass
Substituting the given values:
acceleration = 215.25 N (net force) / 25 kg (mass) = 8.61 m/s^2
Therefore, the acceleration of the box is 8.61 m/s^2.