Use the KE and GPE equations to solve for speed or height depending on the situation.

A 1-kg model airplane has 12.5 joules of kinetic energy *and* 98 joules of gravitational potential energy. What is its speed? What is its height?

hoiuu Feb 5, 2019

#1**+1 **

Answer:

**speed: 5 m/s height: 9.99 m **

Explanation:

KE=12mv2

kinetic energy = 12 * mass * velocity squared

12.5J=12⋅1kg⋅v2

1⋅v2=25J

v2=25J

v=±5J

since speed does not specify direction as velocity does, we can take the value of 5m/s for speed.

GPE=mgh

gravitational potential energy = mass * gravitational field strength * height

assuming the airplane is flying above Earth, the gravitational field strength is 9.81N/kg.

98J=1kg⋅9.81J⋅h

98J=9.81h

9.81h=98

h=989.81=9.99

h=9.99m

itsyaboi Feb 5, 2019