Using the law of conservation of angular momentum, we have
<span>I1 w1 = I2 w2 </span>
<span>ie., m1r^2/2 x w1 = ( m1r^2/2 + m2r^2 ) w2 </span>
<span>ie., new angular velocity w2 = m1 w1 / ( m1+ 2m2) = 125 x 3.1 / ( 125 + 2 x39.5 ) </span>
<span>= 1.8995 = 1.9 rad /sec ( nearly )</span>
Answer:
The pitch that he hears after the truck passes and is moving away is 819.6 Hz.
Explanation:
The pitch that he hears after the truck passes and is moving away can be calculated using the following equation:

Where:
: is the perceived frequency
: is the emitted frequency
: is the speed of sound = 340 m/s
: is the speed of the observer = 0 (he is not moving)
: is the speed of the fire truck
First, we need to find the speed of the fire truck. When it approaches the observer we have:




Hence, the speed of the fire truck is 25.05 m/s.
Now, we can calculate the pitch that the observer hears after the truck passes:



Therefore, the pitch that he hears after the truck passes and is moving away is 819.6 Hz.
I hope it helps you!
Answer:
7 m/s
Explanation:
Acceleration, 
Where v and u are the final and initial velocities of the Justine respectively, t is the time taken for Justin to attain final velocity.
Making v the subject then
v=at+u
Taking u as zero then
Substituting 3.5 for t, 2 as a then
v=3.5*2=7 m/s
m₁ = mass of sample of copper = m₂ = mass of sample of aluminum = 5 g
T = initial temperature of copper = initial temperature of aluminum
T₁ = final temperature of copper
T₂ = final temperature of aluminum
c₁ = specific heat of copper = 0.09 cal/g°C
c₂ = specific heat of aluminum = 0.22 cal/g°C
Since both receive same amount of heat, hence
Q₁ = Q₂
m₁ c₁ (T₁ - T) = m₂ c₂ (T₂ - T)
(5) (0.09) (T₁ - T) = (5) (0.22) (T₂ - T)
T₁ - T = (2.44) (T₂ - T)
Change in temperature of copper = (2.44) change in temperature of aluminum
hence the correct choice is
c. The copper will get hotter than the aluminum.
Given that,
mass m= 5.7 kg
Force of gravity = ?
Since,
Force of gravity acting on earth is equal to the weight and
W= mg
W= 5.7 * 9.81
W= 55.917
or
W= 56 N
Force of gravity acting on Earth by the package is 56 N.