A 2000 kg car is moving with a velocity of 50 km/hr. What is its kinetic energy? If the car reduces its speed by half, by what factor is the kinetic energy changed?
ke= 1/2 M V^2
I will be happy to critique your thinking.
ke=1/2*2000kg*50
ke=50000
No. first, you have to have velocity in m/s. Convert km/hr.
Second, thequatioon says square velocity.
To calculate the kinetic energy of an object, you need to use the formula:
Kinetic energy = (1/2) * mass * velocity^2
Given that the mass of the car is 2000 kg and the velocity is 50 km/hr, you first need to convert the velocity to meters per second (m/s), as the SI unit for mass is kilograms (kg) and the SI unit for velocity is meters per second (m/s).
To convert km/hr to m/s, you can use the conversion factor:
1 km/hr = (1/3.6) m/s
So, 50 km/hr = (50 * (1/3.6)) m/s = 13.89 m/s
Now, you can substitute the values into the kinetic energy formula:
Kinetic energy = (1/2) * 2000 kg * (13.89 m/s)^2
Simplifying the formula:
Kinetic energy = 1/2 * 2000 kg * 192.84 m^2/s^2
= 2000 kg * 96.42 m^2/s^2
= 192840 J (Joules)
Therefore, the kinetic energy of the car is 192840 Joules.
Now, let's calculate the change in kinetic energy when the car reduces its speed by half. The new velocity will be half of the initial velocity, which means the new velocity will be 6.94 m/s.
Using the same formula as above, with the new velocity:
New Kinetic energy = (1/2) * 2000 kg * (6.94 m/s)^2
Simplifying the formula:
New Kinetic energy = 1/2 * 2000 kg * 48.14 m^2/s^2
= 2000 kg * 24.07 m^2/s^2
= 48140 J (Joules)
The change in kinetic energy can be calculated by subtracting the new kinetic energy from the initial kinetic energy:
Change in kinetic energy = Initial kinetic energy - New kinetic energy
= 192840 J - 48140 J
= 144700 J (Joules)
To determine the change in kinetic energy as a factor, divide the change in kinetic energy by the initial kinetic energy:
Change in kinetic energy as a factor = Change in kinetic energy / Initial kinetic energy
= 144700 J / 192840 J
= 0.75 (rounded to two decimal places)
The kinetic energy is reduced by a factor of 0.75 (or 75%) when the car reduces its speed by half.