a racecar has a mass of 1500 kg. what is the KE in joules if it has a speed of 110 km/hr
Answers only work once. Try to learn the methods.
You probably know the formula
Kinetic energy K = (1/2)mv^2
The answer is in Joules if the mass in kg and speed is in metres per second.
This really is not too hard. Try not to give up so easily.
The only difficulty is that the speed is given as 110 km/hr
110 km is 110,000 metres
1 hour is 3600 seconds
You knew that.
So, 110 km/hr is 110,000 metres/3600 seconds = 275/9 metres /sec
Now just put m = 1500 kg and v = 275/9 metres /sec into the equation.
K = (1/2)*1500*(275/9)^2
Now let a calculator take the strain.
K = 700231.48 Joules
In round figures, just over 700 kiloJoules
Read this through until you feel you could do another one like it in an exam.
Regards - Ian
110,000/3600 = 30.555