Compare the kinetic energies of the following:
a) A baseball (mass=0.145kg) moving at 100 km/h.
b) A runner (mass = 75 kg) moving at 30km/h.
c) A swimmer (mass = 75 kg) moving at 7 km/h.
d) A discus (mass = 2 kg) moving at 20 m/s.
to convert km/hr to m/s either use Google or head.
for example
7 km/hr(1 hr/3600 seconds)(1000 m/km)
= 7 /3.6
To compare the kinetic energies of the given objects, we need to use the formula for kinetic energy:
Kinetic energy (K.E.) = 0.5 * mass * velocity^2
Let's calculate the kinetic energies for each object:
a) The baseball has a mass of 0.145 kg and is moving at a velocity of 100 km/h. First, we need to convert the velocity to m/s since the formula requires the velocity in meters per second. 1 km/h = 1000 m/3600 s, so 100 km/h = (100 * 1000) / 3600 m/s ≈ 27.78 m/s.
K.E. of baseball = 0.5 * 0.145 kg * (27.78 m/s)^2
b) The runner has a mass of 75 kg and is moving at a velocity of 30 km/h. Converting the velocity to m/s: 30 km/h = (30 * 1000) / 3600 m/s ≈ 8.33 m/s.
K.E. of runner = 0.5 * 75 kg * (8.33 m/s)^2
c) The swimmer also has a mass of 75 kg but is moving at a velocity of 7 km/h. Converting the velocity to m/s: 7 km/h = (7 * 1000) / 3600 m/s ≈ 1.94 m/s.
K.E. of swimmer = 0.5 * 75 kg * (1.94 m/s)^2
d) The discus has a mass of 2 kg and is moving at a velocity of 20 m/s.
K.E. of discus = 0.5 * 2 kg * (20 m/s)^2
Now, we can calculate the kinetic energies for each object:
a) K.E. of baseball = 0.5 * 0.145 kg * (27.78 m/s)^2 ≈ 8.40 J (Joules)
b) K.E. of runner = 0.5 * 75 kg * (8.33 m/s)^2 ≈ 208 J
c) K.E. of swimmer = 0.5 * 75 kg * (1.94 m/s)^2 ≈ 56 J
d) K.E. of discus = 0.5 * 2 kg * (20 m/s)^2 = 400 J
Comparing the calculated kinetic energies, we find:
- The baseball has a kinetic energy of approximately 8.40 Joules.
- The runner has a kinetic energy of approximately 208 Joules.
- The swimmer has a kinetic energy of approximately 56 Joules.
- The discus has a kinetic energy of 400 Joules.
Therefore, the kinetic energy of the discus is the highest among the given objects, followed by the runner, baseball, and swimmer respectively.