Answer:

Explanation:
The potential energy (PE) we are looking here is gravitational potential energy (GPE).
GPE= mgh,
where m is the mass of an object,
g is the gravitational field strength
h is the height of the object
KE= ½mv²,
where m is the mass and v is the velocity
loss in GPE= gain in KE
mgh= ½mv²
gh= ½v² (<em>divide by m throughout</em>)
Assuming that the object is on earth, then g= 10N/Kg
½v²= 10h (<em>substitute g=10</em>)
v²= 20h (<em>×2 on both sides</em>)
v= √20h (<em>square root both sides</em>)