Answer:
Explanation:
It means that you only need apply 1/4th of the actual force required to operate the lever as you have an mechanical advantage which permits you to do 4 times the work with the same amount of effort.
Answer:
Pi(3.14) radians or 180º degrees
Explanation:
First of all, we need to obtain the wavelength of a wave traveling to the speed of sound and 420 Hz of frequency.
The formula is:

where l = wavelength in meters
With current values:
l = 336 [m/s]/420[1/s] = 0.8 meters
Since a complete cycle (360º or 2pi radians) needs 0.8 meters to complete, 0.4 meters or 40 cm is just half of it, making a 180º degree phase or 3.14 radians.
Answer:
59.51 mph.
Explanation:
The following data were obtained from the question:
Distance (d) = 147 miles
Time (t) = 2.47 hours.
Speed (S) =?
Speed is defined as the distance travelled per unit time. Mathematically, it is expressed as:
Speed (S) = Distance (d) / time (t)
S = d/t
With the above formula, we can obtain the speed of the girl as illustrated below:
Distance (d) = 147 miles
Time (t) = 2.47 hours.
Speed (S) =?
S = d/t
S = 147 miles / 2.47 hours.
S = 59.51 miles per hour (mph)
Thus, the speed of the girl is 59.51 mph.
Answer:
d)2.13 C s⁻¹
Explanation:
Rate of flow of heat through walls
=
K = .33
A = 6 X .4 X .4 =0.96
T₂-T₁ = 30+40 = 70
d = 5 x 10⁻³
Put these data in the relation above
Rate of flow of heat
= 
= 4435.2 Js⁻¹
Specific heat of gas = 2.5 R = 20.785 J
Rise in temp = 
= 2.13 degree celsius.
Answer:
The value of current through the rod becomes half

Explanation:
As per Ohm's law we know that the current through a resistor is given as

here we know that

here we know that the length of the cylinder is L and area is A so the value of current through the rod is given as

now we have change the length of the conductor to twice of initial value and rest all parameters will remain the same
so we will have

now from above two equations we have

so new current will become
