Answer:
it would take him 1 minute to run 304.5 meters and 1 second to run 5.075 meters
Explanation:
Before anything, if you are lifting the Work value have to be negative, reason is because the formula to the work of the weight is:
*Photo to help you to visualize. (P = Weight Force, F = Force)
If you are lifting, you are exercising a force that opposes the Weight Force, Force up (lifting) and Weight Force down (gravity pulling).
This forms a 180 angle and the cos 180 = -1.
Well let's do the question:
Work (W) = -40 J (Joule = Kg x m^2/s^2)
(negative, explanation given)
Weight Force (P) = 10 N (Newton = kg x m/s^2)
Distance (D) = ?
W = P x d x cos theta
-> -40 = 10 x d x -1
-> -40 = -10 x d
-> d = -40/-10 (J/N)
-> d = 4 meters
The question appears to be incomplete.
I assume that we are to find the coefficient of static friction, μ, between the desk and the book.
Refer to the diagram shown below.
m = the mass of the book
mg = the weight of the book (g = acceleration due to gravity)
N = the normal reaction, which is equal to
N = mg cos(12°)
R = the frictional force that opposes the sliding down of the book. It is
R = μN = μmg cos(12°)
F = the component of the weight acting down the incline. It is
F = mg sin(12°)
Because the book is in static equilibrium (by not sliding down the plane), therefore
F = R
mg sin(12°) = μmg cos(12°)
Therefore, the static coefficient of friction is
μ = tan(12) = 0.213
Answer: μ = 0.21 (nearest tenth)
Answer:
10.01 cm
Explanation:
Given that,
The time delay between transmission and the arrival of the reflected wave of a signal using ultrasound traveling through a piece of fat tissue was 0.13 ms.
The average propagation speed for sound in body tissue is 1540 m/s.
We need to find the depth when the reflection occur. We know that, the distance is double when transmitting and arriving. So,
or
d = 10.01 cm
So, the reflection will occur at 10.01 cm.