Answer:
54 W
Explanation:
Power = Voltage* Current =V*I = 120V*0.45A =54 Watt
I am pretty sure that infrared waves are part of the electromagnet spectrum produces heat and with special equipment can locate people at night. I choose this options because <span>gamma rays can be harmful to people, and other options just make no sense.</span>
Answer:
They will not stop at same elevation
for v=10m/2 => h=5.1m
for v=20m/2 => h=20.4m
Explanation:
If we neglect the effects of friction in the calculations the energy if the system must be conserved. The car energy can be described as a combination of kinetic energy and potential energy:
The potential energy is due to the gravitational forces and can be describes as:
Where g is the gravitation acceleration, m the mass of the car, and h the elevation. This elevation is a relative quantity and any point of reference will do the work, in this case we will consider the base of the hill as h=0.
The kinetic energy is related to the velocity of the car as:
As the energy must be constant E will be always constant, replacing the expressions for kinetic and potenctial energy:
In the base of the hill we have h=0:
When the car stops moving we have v=0:
This two must be equal:
solving for h:
Lets solve for the two cases:
for v=10m/2 => h=5.1m
for v=20m/2 => h=20.4m
As you can see, when the velocity is the double the height it reaches goes to four times the former one.
Answer:
The acceleration at the astronaut's head decreases.
Explanation:
Since the centripetal acceleration equals acceleration due to gravity,
a = g = GM/R². since a changes infinitesimally from his foot to his head, we differentiate a with respect to r to get da/dr = -2GM/R³.
So, da, the change in acceleration = -2GMdR/R³ = -2gdR/R = -2 × 9.8/6.4 × 10⁶ m = -3.0625 × 10⁻⁶dR m/s².
Since dR = height of astronaut = 1.80 m, da = -3.0625 × 10⁻⁶ × 1.8 = -5.5125 × 10⁻⁶ m/s².
So the acceleration at the astronaut's head is g + da = 9.8 - 0.0000055125 = 9.7999944875 m/s².
So the acceleration at the astronaut's head decreases.