I don't like the wording of any of the choices on the list.
SONAR generates a short pulse of sound, like a 'peep' or a 'ping',
focused in one direction. If there's a solid object in that direction,
then some of the sound that hits it gets reflected back, toward the
source. The source listens to hear if any of the sound that it sent
out returns to it. If it hears its own 'ping' come back, it measures
the time it took for the sound to go out and come back. That tells
the SONAR equipment that there IS a solid object in that direction,
and also HOW FAR away it is.
RADAR works exactly the same way, except RADAR uses radio waves.
Answer:
a)1.37 s
b)∞ ( Infinite)
Explanation:
Given that
L= 47 cm ( 1 m =100 cm)
L= 0.47 m
a)
On the earth :
Acceleration due to gravity = g
We know that time period of the simple pendulum given as
Here
Now by putting the values
T=1.37 s
b)
Free falling elevator :
When elevator is falling freely then
( This is case of weightless motion)
Therefore
T=∞ (Infinite)
Answer: - 452.088joule
Explanation:
Given the following :
Mass of water = 12g
Change in temperature(Dt) = (11 - 20)°C = - 9°C
Specific heats capacity of water(c) = 4.186j/g°C
Q = mcDt
Where Q = quantity of heat
Q = 12g × 4.186j/g°C × - 9°C
Q = - 452.088joule
Answer:
As the skydiver falls to the Earth, she experiences positive acceleration only due to gravity.
Explanation:
As the skydiver falls to the Earth, she experiences friction in the form of air resistance which tries to slow her down and is proportional to the her velocity. So it cannot have a positive acceleration as it acts in opposite direction to slow her down.
Inertia during skydiving is experienced when we open an parachute, the parachute slows down the speed of are descent hence changing our inertia of motion with a velocity.
Only the Earth's, gravitational field has an positive acceleration as it pulls us towards the Earth, hence increasing our velocity.
Answer:
the minimum value of torque is 101.7 N-m.
Explanation:
Given that,
Mass of bundle of shingles, m = 30 kg
Upward acceleration of the shingles,
The radius of the motor of the pulley, r = 0.3 m
Let T is the tension acting on the shingles when it is lifted up. It can be calculated as :
T-mg=ma
T=m(g+a)
Let 
is the minimum torque that the motor must be able to provide. It is given by :
the minimum value of torque is 
