Answer:
A. 12 m/s
Explanation:
Let’s remember that the definition of velocity is the variation of position of an object respect with to time. We know that the boy dropped the stone when the boat was 27 meters from the bridge and the stone hit the water 3 meters in front of the boat. So, the Boat must have traveled x=27 m-3m=24 m. The next step is calculating the amount of time that took the boat to make that travel; coincidentally, it is the same time that takes the stone to reach the water.
The equation that describes the motion of the stone is:
y = y_0 + v_0 * t+1/2 * a * t^2
The boy drops the stone from rest, so we can say that v_0=0. We can fixate the reference line on top of the bridge, so y_0=0 as well. The equation will be then:
-19,6 m = -1/2 * 9,8 m/s^2 * t^2
t^2= -(19,6 m)/(-4,9 m/s^2) = 4,012 s^2
t=√(4,012 s^2) = 2,003 s
Knowing the time that takes the stone to reach the water, that is the same that time that the boat uses to travel the 24 meters. The velocity of the boat is:
v = ∆x/∆t = (27 m-3 m)/(2,003 s-0s) = 11,9816 m/s ≈ 12 m/s
Have a nice day! :D
Answer:
6.8 m/s2
Explanation:
Let g = 9.8 m/s2. The total weight of both the rope and the mouse-robot is
W = Mg + mg = 1*9.8 + 2*9.8 = 29.4 N
For the rope to fails, the robot must act a force on the rope with an additional magnitude of 43 - 29.4 = 13.6 N. This force is generated by the robot itself when it's pulling itself up at an acceleration of
a = F/m = 13.6 / 2 = 6.8 m/s2
So the minimum magnitude of the acceleration would be 6.8 m/s2 for the rope to fail
Answer:
degrees
Explanation:
Eels have been recorded to spin at up to 14 revolutions per second when feeding in this way
So the angle the eel rotate is going to be
Camera record 120 frames per second
time taken for 1 frame record
eel rotates
degrees in 1 second
so:
eel rotetas degrees
Answer:
Explanation:
According to the Stefan-Boltzmann law for real radiating bodies:
(1)
Where:
is the energy radiated (in Watts)
is the Stefan-Boltzmann's constant.
is the Surface area of the body
is the effective temperature of the body (its surface absolute temperature) in Kelvin
is the body's emissivity
On the other hand, we are told the human body is roughly approximated to a cylinder of length 
and circumference 
.
The circumference of a circle is:
where 
is the radius. Hence 
.
Now we have to input this value for in the Area of a cylinder formula:
(2)
Substituting (2) in (1):
(3)
Finally:
Answer:
Both objects travel the same distance.
Explanation:
The two object have the same kinetic energy.
4 x 2^2/2. = 1x 4^2/2
= 8
