A baseball with a mass of 0.145 kg is thrown straight down at the ground. At a particular speed, it has a drag force of 0.4 N acting on it. What is its acceleration at that time?
a. -7.0 m/s2
b. -2.8 m/s2
c. -9.8 m/s2
d. -12.6 m/s2
.4 N up
9.8*.145 down
m a = .4 - 9.8*.145
that is about .4 - 1.4 or -1
a = -1/.145 = about -7
a
To find the acceleration of the baseball, 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.
In this case, the only force acting on the baseball is the drag force. Therefore, the net force is equal to the drag force.
Given that the drag force is 0.4 N, we can substitute this value into the equation:
0.4 N = mass * acceleration
The mass of the baseball is given as 0.145 kg, so the equation becomes:
0.4 N = 0.145 kg * acceleration
Now, we can solve for the acceleration by dividing both sides of the equation by 0.145 kg:
acceleration = 0.4 N / 0.145 kg
Simplifying this equation gives us:
acceleration ≈ 2.76 m/s^2
The acceleration is positive, indicating that the baseball is moving downward. However, since the question asks for the magnitude of the acceleration, we can disregard the sign and choose the closest answer choice, which is:
b. -2.8 m/s^2
To find the acceleration of the baseball, we need to use Newton's second law of motion, which states that the acceleration of an object is equal to the net force acting on it divided by its mass.
First, we need to determine the net force acting on the baseball at that particular speed. The net force is the difference between the force due to gravity and the drag force.
The force due to gravity can be calculated using the formula:
Force due to gravity = mass * acceleration due to gravity
The acceleration due to gravity on Earth is approximately 9.8 m/s^2.
Force due to gravity = 0.145 kg * 9.8 m/s^2 = 1.431 N
Now, subtract the drag force from the force due to gravity to find the net force:
Net force = Force due to gravity - Drag force
Net force = 1.431 N - 0.4 N = 1.031 N
Finally, we can calculate the acceleration using Newton's second law:
Acceleration = Net force / mass
Acceleration = 1.031 N / 0.145 kg ≈ -7.103 m/s^2
Rounded to one decimal place, the acceleration of the baseball is approximately -7.1 m/s^2.
Therefore, the correct answer is a. -7.0 m/s^2.