A 67.0 kg person, standing on a diving board, dives straight down into the water. Just before striking the water, her speed is 5.50 m/s. At a time of 1.75 s after she enters the water, her speed is reduced to 1.10 m/s. What is the net average force (magnitude and direction) that acts on her when she is in the water?
uuhh.. F=ma?
Kinematic description of decelerated motion of the diver gives
V=Vo-a•t
a = (Vo-V)/t = (5.5-1.1)/1.75 = 2.51 m/s^2.
From Newton’s 2 law
F = m•a = 67•2.51=168.5 N
Yes, you are correct. To find the net average force acting on the person, we can use Newton's second law of motion, which states that the force (F) acting on an object is equal to the mass (m) multiplied by the acceleration (a):
F = m * a
In this case, the person's mass (m) is 67.0 kg. To calculate the acceleration, we need to find the change in velocity (Δv) and the time interval (Δt).
Δv = final velocity - initial velocity
= 1.10 m/s - 5.50 m/s
= -4.40 m/s
Δt = time final - time initial
= 1.75 s - 0 s
= 1.75 s
Now we can find the acceleration (a) using the equation:
a = Δv / Δt
= (-4.40 m/s) / (1.75 s)
= -2.51 m/s²
Since the person is being decelerated, the acceleration is negative.
Finally, we can substitute the known values into Newton's second law to find the net average force:
F = m * a
= (67.0 kg) * (-2.51 m/s²)
≈ -168.17 N
The net average force acting on the person in the water is approximately 168.17 N in the upward direction (+y direction) because it opposes the motion.
Yes, you're on the right track! To calculate the net average force acting on the person, we can use Newton's second law, which states that force is equal to mass multiplied by acceleration (F = ma).
However, in this case, we don't have the person's acceleration directly given. Instead, we have information about her initial and final speed, as well as the time it takes for the change to occur. To find the acceleration, we can use the equation:
Acceleration (a) = (Final velocity - Initial velocity) / Time
Let's plug in the given values:
Initial velocity (u) = 5.50 m/s
Final velocity (v) = 1.10 m/s
Time (t) = 1.75 s
Using the equation, we can calculate the acceleration:
a = (v - u) / t = (1.10 m/s - 5.50 m/s) / 1.75 s
Now that we have the acceleration, we can proceed to calculate the net average force. Since the person is in water and the force acting on her is given by the water, we can use the equation:
Net average force (F) = mass (m) * acceleration (a)
Given mass (m) = 67.0 kg, we can calculate the force:
F = 67.0 kg * acceleration (a)
Finally, we have our answer. Please calculate the acceleration value and then multiply it by the mass to find the net average force.