Answer:
5.625km/h
Explanation:
We are given that
Distance between home and market, d=2.5 km
Speed, v1=5km/h
Speed, v2=7.5 km/h
We have to find the average speed of the man over the interval of time 0 to 40min.
Time,
Using the formula
1 hour =60 min
Distance traveled by man in 10 min with speed 7.5 km/h=
Therefore,
Total distance covered=2.5+2.5/2=3.75 km
Time=40 min=40/60=2/3 hour
Average speed=
Average speed=
Well, the relationship between the net force and mass and acceleration of an object are directly related, as per the equation - Fnet = ma.
Thus the solution is A. As the net force of an object decreases, the object's acceleration also decreases, mass is kept constant.
Option ( c ) is correct.
Using the formula for power
P= power
i= current= 0.4 A
R= resistance= 30 ohm
so power= (0.4)² (30)
Power=4.8 W
Answer: The size of the whale can be estimated by using echo Sounder or Sonar
Explanation:The researchers and physicst uses the knowledge of reflection of sound in water or echo to solve a lot of puzzle under water , including calclulating the distance and size of objects like fish,sunk ship,etc
The sonar is able to receive the signals from the whales and the succesive echoes that follows when placed in a strategic position in the water in the path of the whale .
The sonar has a traducers which has both a transmitter and a receiver,so it receives pulses from the whale and transmit back same echo back to the whale and to the bottom of the sea.
Using the speed of sound underwater and time taken for succesive echoes of pulses ,it can calculate with the precision the location of the whale while the image of the whale is also capture by the traducers to determine the size.
I think the complete question is:
An old movie poster used a quote "In space, no one can hear you scream!" Which of these best explains the quote?
A) The quote is incorrect, you can hear sound in outer space.
B) Sound cannot be polarized. So, you cannot hear sound in space.
C) Sound is an electromagnetic wave and needs no medium to travel through.
D) Sound needs a medium for the wave to vibrate and there is nothing in space to vibrate.
Answer:
D) Sound needs a medium for the wave to vibrate and there is nothing in space to vibrate.
Explanation:
There are two types of waves:
- Mechanical Waves : These waves requires are medium to travel from one point of space to another point of space. Sound wave is one such example. Since they depend upon medium so speed of travelling also depend upon medium.
- Electromagnetic Waves : These type of waves do not require a medium to travel. If medium exists then it will cause some hindrance in there path but still they will travel. For example: Light waves, X-Rays, Microwaves, Infrared waves, Ultraviolet waves etc.
In space no particle exists so no mechanical waves, such as sound, can travel through it but any electromagnetic wave can travel, such as light. That is why when astronauts are in space walk or when they are in outer space then they do not talk rather they use sign language to communicate
