A horizontal force of 20 N acted on a 10 kg mass at rest. The force accelerated the mass over a rough surface so that the mass had a speed of 6.0 m/s after 5.0 seconds. How much friction was acting on the mass?
Net force=ma
(20N-frictionforce)=10kg*6/5
solve for friction force
To find the friction acting on the mass, we need to calculate the net force acting on the mass and then subtract the applied force.
First, let's find the net force. We can use 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. The formula for Newton's second law is:
Fnet = m * a
Where:
Fnet is the net force (unknown)
m is the mass of the object (10 kg)
a is the acceleration of the object (unknown)
Now, to find the acceleration, we can use the kinematic equation:
v = u + at
Where:
v is the final velocity (6.0 m/s)
u is the initial velocity (0 m/s, since the mass is at rest)
a is the acceleration (unknown)
t is the time (5.0 seconds)
Rearranging the equation to solve for acceleration:
a = (v - u) / t
Substituting the given values:
a = (6.0 m/s - 0 m/s) / 5.0 s
a = 1.2 m/s^2
Now, we can calculate the net force:
Fnet = m * a
Fnet = 10 kg * 1.2 m/s^2
Fnet = 12 N
Since the applied force is given as 20 N, we can subtract the applied force from the net force to find the friction force:
Friction force = Fnet - Applied force
Friction force = 12 N - 20 N
Friction force = -8 N
The negative sign indicates that the friction force is acting in the opposite direction of the applied force. In this case, the friction force is 8 N and acts in the opposite direction of the applied force.