A 75 kg bobsled is pushed along a horizontal surface by two athletes. After the bobsled is pushed a distance of 4.5 m starting from an initial speed of 1.2 m/s, its speed is 6.0 m/s. What is the change in kinetic energy? Find the magnitude of the net force on the bobsled.
WC East?
To find the change in kinetic energy, we use the equation:
ΔKE = KEf - KEi
Where ΔKE is the change in kinetic energy, KEf is the final kinetic energy, and KEi is the initial kinetic energy.
The formula for kinetic energy is:
KE = 0.5 * m * v^2
Where KE is the kinetic energy, m is the mass of the object, and v is its velocity.
Let's calculate the initial and final kinetic energies:
Initial kinetic energy (KEi) = 0.5 * m * v^2
= 0.5 * 75 kg * (1.2 m/s)^2
Final kinetic energy (KEf) = 0.5 * m * v^2
= 0.5 * 75 kg * (6.0 m/s)^2
Now we can substitute these values into the equation for the change in kinetic energy:
ΔKE = KEf - KEi
= (0.5 * 75 kg * (6.0 m/s)^2) - (0.5 * 75 kg * (1.2 m/s)^2)
To calculate the magnitude of the net force on the bobsled, 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:
Fnet = m * a
We can calculate the acceleration using the equation for average acceleration, which is:
a = (vf - vi) / t
Where a is acceleration, vf is final velocity, vi is initial velocity, and t is the time taken. In this case, the time is not given. However, we can calculate it using the distance covered and average velocity:
t = d / vavg
Where d is the distance covered and vavg is the average velocity.
So, let's calculate the time taken:
t = 4.5 m / ((1.2 m/s + 6.0 m/s) / 2)
Now, substitute the calculated time into the equation for acceleration:
a = (6.0 m/s - 1.2 m/s) / t
Finally, substitute the mass and acceleration values into the equation for net force:
Fnet = m * a
By following these steps, you can find both the change in kinetic energy and the magnitude of the net force on the bobsled.