Answer:

Given:
Force = 8 N
Distance covered by the body = 50 cm = 0.5 m
Explanation:
Work Done = Force × Distance covered by the body
= 8 × 0.5
= 4 J
Answer:
Yes
Explanation:
The core of an electromagnet serves to stabilize the magnetic field created by the wire. The thicker the core, the more metal there is to amplify the current. Therefore, a thicker core does make an electromagnet stronger. Hope this helps!
Answer: 60m/s
Explanation:
The wavespeed is the distance covered by the wave in one second. It is measured in metre per second, and represented by the symbol V
Wavespeed (V) = Frequency F x wavelength λ
i.e V = F λ
In the first case:
Wavespeed = 30 m/s
Frequency of sound = 6Hz
Wavelength = 5m
In the second case:
Wavespeed = ?
Frequency of sound = (2x 6Hz = 12Hz)
Wavelength = 5m (remains constant)
Apply V = F λ
Wavespeed = 12 Hz x 5m
Wavespeed = 60m/s
Therefore, when frequency is doubled, the speed is also doubled. Thus, the new speed of the wave is 60m/s
If the net force on a block is zero, the block will move at constant velocity
Explanation:
We can answer this question by applying Newton's second law of motion, which states that the net force on an object is equal to the product between its mass and its acceleration:
(1)
where
is the net force on the object
m is its mass
a is its acceleration
In this problem, we have a block, and the net force on it is zero:

According to eq.(1), this also implies that

So, the acceleration of the block is zero.
However, acceleration is the rate of change of velocity of a body:

where
is the change in velocity in a time of
. Since the acceleration is zero, this means that
, and therefore the velocity of the object is constant.
Learn more about Newton's second law:
brainly.com/question/3820012
#LearnwithBrainly
Answer:
d = 380 feet
Explanation:
Height of man = perpendicular= 130 feet
Angle of depression = ∅ = 70 °
distance to bus stop from man = hypotenuse = d = 130 sec∅
As sec ∅ = 1 / cos∅
so d = 130 sec∅ or d = 130 / cos∅
d = 130 / cos(70°)
d = 380 feet