A block of weight 7.0N rest on a level floor. The frictional force between the block and the floor is 1.0N. A horizontal force of 1.4N is used to pull the block for 4seconds. What is the velocity of the block after this time
acceleration = net force / mass = (1.4 N - 1.0 N) / (7.0 N / g) ... m/s^2
velocity = acceleration * time
F = 1.4 N., Ff = 1 N.
Mg = 7, M = 7/g = 7/9.8 = 0.71 kg. = Mass of the block.
F-Ff = M*a.
1.4-1 = 0.71a
a = 0.56 m/s^2.
V = Vo+a*T = 0+0.56*4 = __ m/s.
To find the velocity of the block after 4 seconds, you can use Newton's second law of motion. According to this law, the net force acting on an object is equal to the product of its mass and acceleration.
In this case, the net force acting on the block is the difference between the applied force and the frictional force, as the block is being pulled horizontally.
Net Force = Applied Force - Frictional Force
First, we need to calculate the acceleration of the block using Newton's second law of motion:
Net Force = Mass * Acceleration
Rearranging the formula, we get:
Acceleration = Net Force / Mass
Given that the weight of the block is the same as its mass (weight = mass * gravitational acceleration, and the gravitational acceleration is approximately 9.8 m/s²), we have:
Weight of the block = 7.0 N
Next, we calculate the net force:
Net Force = Applied Force - Frictional Force
= 1.4 N - 1.0 N
= 0.4 N
Now, we can substitute the values into the formula for acceleration:
Acceleration = Net Force / Mass
= 0.4 N / 7.0 N (mass = weight = 7.0 N)
= 0.057 m/s²
Now that we have the acceleration, we can calculate the velocity using the kinematic equation:
Velocity = Initial Velocity + Acceleration * Time
As the block starts from rest (initial velocity = 0), the equation becomes:
Velocity = 0 + Acceleration * Time
= 0 + 0.057 m/s² * 4 s
= 0.228 m/s
Therefore, the velocity of the block after 4 seconds is 0.228 m/s.