You can't get something from nothing is practically stating the law. The law means states that energy can't be created or destroyed, in other words, it's constant. So in saying so, you truly can't get something from nothing
Answer:
c) 1.0 kg
Explanation:
The mass of the stick will be located at the centre of the metre rule. Since the rock is located 0.25m from the pivot, the mass of the meter rule is also 0.25m to the Right of the support
According to law of moment
Sum of clockwise moment = sum of anti clockwise moments
Clockwise moment = M×0.25(mass of metre rule is M)
CW moment = 0.25M
Anti clockwise moment = 0.25×1
ACW moments = 0.25kgm
Equate;
0.25M = 0.25
M = 0.25/0.25
M = 1.0kg
Hence the mass of the metre rule is 1.0kg
B should be the answer
Look at this example to help you
Here's the formula for the distance covered by an accelerating body in some amount of time ' T '. This formula is incredibly simple but incredibly useful. It pops up so often in Physics that you really should memorize it:
D = 1/2 a T²
Distance = (1/2)·(acceleration)·(time²)
This question gives us the acceleration and the distance, and we want to find the time.
(9,000 m) = (1/2) (20 m/s²) (time²)
(9,000 m) = (10 m/s²) (time²)
Divide each side by 10 m/s²:
(9,000 m) / (10 m/s²) = (time²)
900 s² = time²
Square root each side:
<em>T = 30 seconds</em>