contestada

a small dog is trained to jump straight up a distance of 1.2m. How much kinetic energy does the 7.2kg dog need to jump this high? ( the acceleration due to gravity is 9.8m/s2)

Respuesta :

hisroyal1
We are told to find the Kinetic Energy required by the dog

Energy = Force * Distance

According to the question,
Distance = 1.2 m
But we are not given any value for the Force

However, we know that,
Force = Mass * Acceleration

According to the question,
Mass = 7.2kg
Acceleration = 9.8 m/s²

Therefore, 
Force = 7.2 * 9.8
Force = 70.56 Newton

Remember, what we are looking for is the Energy
Energy = Force * Distance
Now we know that Force = 70.56 Newton
Distance = 1.2 m

Therefore,
Energy = 70.56 * 1.2
Energy = 84.7 Joules
AL2006
When the pooch is 1.2m off the ground,
her potential energy is ...

                (m) ·(g) ·(h)

            = (7.2 kg) ·(9.8 m/s² ) ·(1.2 m)

            =         84.7 joules .

If she doesn't leave the ground with AT LEAST that much
kinetic energy, she'll never make it to 1.2 m.