Conservation of momentum and energy: Self Test

Assuming that air friction is negligible, how much kinetic energy does it have when it hits the ground?  Calculate the answer yourself if you can.

Hint: First Calculate the potential energy at the top

Potential energy at top = weight • height

Remember weight = mass • gravity = mg

PE = mg • height

1. PE = kg • m/s² • m
2. PE = (kg • m/s²) • m
3. PE = newton • m
4. PE = joules

What is the speed of the rock just before it hits the ground (approximate your answer)? m/s

One block of ice has a mass of 12 Kg and the other's mass is 18 kg.  The dynamite explodes.  If the block of lesser mass moves off with a speed of 10 m/s, what is the speed of the more massive block?

m/s

Please type in the answer as it is wither it has a negative sign or not

If the two cars stick together, what is their speed immediately after the collision?

Hint: On both sides of the equation, you may use "pounds" for mass and "miles per hour" for velocity.  This is permissible because weight (pounds) is proportional to mass, and miles/hour is a legitimate unit of velocity.)

miles/hour

joules

approximate your answer without decimal points

watts

From how high did it fall?

meters

Hint: Since the object's mass does not matter, you may choose any mass you want. and do not forget to approximate to the nearest first decimal point.