A constant friction force of 15 N acts on a 70 kg skier for 20 s. What is the skier's change in velocity?
a = 15/70 = 0.2143 m/s^2,
a = (Vf - Vo) / t = 0.2143,
(Vf - Vo) / 20 = 0.2143,
(Vf - Vo) = 4.29 m/s = The change in
velocity.
To find the skier's change in velocity, we need to 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 net force is the constant friction force acting on the skier.
First, let's find the acceleration of the skier using the formula:
net force = mass x acceleration
Rearranging the formula, we get:
acceleration = net force / mass
Given that the net force is 15 N and the mass of the skier is 70 kg:
acceleration = 15 N / 70 kg
Now, we can calculate the acceleration:
acceleration = 0.214 m/s²
Next, we can find the change in velocity using the formula:
change in velocity = acceleration x time
Given that the time is 20 s:
change in velocity = 0.214 m/s² x 20 s
Calculating the change in velocity:
change in velocity = 4.28 m/s
Therefore, the skier's change in velocity is 4.28 m/s.
To find the skier's change in velocity, we can use the equation:
Δv = (F × t) / m
where Δv is the change in velocity, F is the friction force, t is the time, and m is the mass of the skier.
In this case, the friction force is 15 N, the time is 20 s, and the mass of the skier is 70 kg.
Substituting the values into the equation:
Δv = (15 N * 20 s) / 70 kg
Now, we can calculate the change in velocity:
Δv = 300 Ns / 70 kg
Dividing the Ns by kg, we get:
Δv ≈ 4.29 m/s
Therefore, the skier's change in velocity is approximately 4.29 m/s.