<span>d
The mass is doubled which means that both the momentum and kinetic energy are also doubled. Also the normal force that's acting along with the coefficient of kinetic friction is also doubled. So the friction that's working to slow down the crate is doubled. So the crate will have double the kinetic energy that needs to be dissipated, but the rate of dissipation is also doubled, so the total time required to dissipate the kinetic energy is the same. And since both crates start out with the same velocity and since they'll lose energy (and velocity) at the same proportional rate, they'll take the same distance to slide to a stop.</span>
In fresh water sound waves travel at 1497m/s at 25 degrees, I'll assume that's the characteristics of the water.
If it's 0.01s then you need to divide the speed by 100 to get the, 14.97, however it gets there and back in that time so you need to halve it.
<u>7.485m</u>
Let's calculate the average acceleration. It is the rate of changing speeds. Hence, we need to calculate the difference of speeds. 10-6=4 m/s. The rate is now
![\frac{4m/s}{2s} =2m/s^2](https://tex.z-dn.net/?f=%20%5Cfrac%7B4m%2Fs%7D%7B2s%7D%20%3D2m%2Fs%5E2)
.
In general, the formula for the mean acceleration between two times 1 and 2 is given by:
![\frac{u_2-u_1}{T}](https://tex.z-dn.net/?f=%20%5Cfrac%7Bu_2-u_1%7D%7BT%7D%20)
where v1 and v2 are the speeds at the respective points and T is the time interval between them.