A 3.00 kg toy falls from a height of 1.00 m. What will the kinetic energy of the toy be just before the toy hits the ground? (Assume no air resistance and that g = 9.81 m/s656-06-03-00-00_files/i0090000.jpg.)

Question

anonymous · Answer

There are several approaches. Try this using the conservation of mechanical energy.
Find the potential energy the object has at the 1.00 m height. That same amount of potential energy will be converted into kinetic energy. Use the formula for kinetic energy, and solve for the final speed.

anonymous · Answer

$$PE=mgh$$
$$KE=\frac{ 1 }{ 2 }mv^2$$

v is velocity
g is -9.8 m/s
h is height
m is the mass

Just before the ball hits the ground the potential energy equals the kinetic energy because it is all converted back into kinetic energy.

so PE = KE
so:$$PE=(3 kg)(-9.8 m/s)(1 m)=KE$$

KE = -29.4

but there is no such thing as negative energy so KE = 29.4 Joules

joules are the unit of energy