Answer:
D. all sounds are caused by vibrations
Explanation:
Molarity and molality both describe the concentration of a substance in terms of moles.
Molarity describes the number of moles of a substance per unit of volume, typically per liter (mol/l).
Molality describes the number of moles per unit of mass, typically kilograms (mol/kg).
When determining the molality of a solution, mol/kg can be obtained by finding the number of moles in the substance, and dividing that number by the the total weight in kilograms of that substance.
When determining the molarity of a solution, mol/l can be obtained by dividing the number of moles in a substance by the total volume in liters of that substance.
Answer:
.
Explanation:
By Newton's Second Law, the acceleration 
of an object is proportional to the net force 
on it. In particular, if the mass of the object is 
, then
.
Rewrite this equation to obtain:
.
In this case, the assumption is that the 
force is the only force that is acting on the object. Hence, the net force on the object would also be
Make sure that all values are in their standard units. Forces should be in Newtons (same as 
, and the acceleration of the object should be in meters-per-second-squared (
). Apply the equation to find the mass of the object.
.
Answer:
Explanation:
a )
While breaking initial velocity u = 62.5 mph
= 62.5 x 1760 x 3 / (60 x 60 ) ft /s
= 91.66 ft / s
distance trvelled s = 150 ft
v² = u² - 2as
0 = 91.66² - 2 a x 150
a = - 28 ft / s²
b ) While accelerating initial velocity u = 0
distance travelled s = .24 mi
time = 19.3 s
s = ut + 1/2 at²
s is distance travelled in time t with acceleration a ,
.24 = 0 + 1/2 a x 19.3²
a = .001288 mi/s²
= 2.06 m /s²
c )
If distance travelled s = .25 mi
final velocity v = ? a = .001288 mi / s²
v² = u² + 2as
= 0 + 2 x .001288 x .25
= .000644
v = .025 mi / s
= .0025 x 60 x 60 mi / h
= 91.35 mph .
d ) initial velocity u = 59 mph
= 86.53 ft / s
final velocity = 0
acceleration = - 28 ft /s²
v = u - at
0 = 86.53 - 28 t
t = 3 sec approx .
<span>The velocity will be 41.25 m/s2 after 9 seconds. To find velocity after a specific time period, multiply the acceleration (2.75) times the number of seconds (9) to receive 24.75 m/s, then add that to the initial velocity of 16.5 m/s. 24.75 + 16.5 = 41.25 m/s2.</span>
