Answer:
0.5 kg
Explanation:
The momentum of an object is defined as
p = mv
where
m is the mass
v is the velocity
In this problem we have,
v = 15 m/s is the velocity of the stone
p = 7.5 kg m/s is the momentum
Solving for m, we can find the mass of the stone:

The change in velocity from 30 m/s north to 40 m/s south is a change of 70 m/s south
Answer:She would need to first know the weight of the sculpture and what she is going to move it with then she will need to use newton's second law to calculate the amount of force needed to move it
Explanation: I just did the assignment on edgunity
Answer:
255 Hz
Explanation:
With 5 beats per second with the 250 Hz fork, we know the unknown fork is either 250 - 5 = 245Hz or 250 + 5 = 255 Hz
With 15 beats per second with the 270 Hz fork, we know the unknown fork is either 270 - 15 = 255Hz or 270 + 15 = 285 Hz (most people would have a hard time discerning 15 beats per second... 5 per second is hard enough)
As 255 is the common frequency, it is the one selected.