Answer:
3.97 m/s
Explanation:
Speed is defined as the distance covered per unit time. Therefore, s=d÷t=d/t
Where d is distance and t is time
Given distance of 5 km and time of 21 minutes the speed would be given by dividing 5 km by 21 min. However, speed is expressed as km/h or m/s or miles per hour etc. So we nees to get our speed in one of these standard units.
Going for m/s
Conversion
1 km has 1000m hence
5 km=5*1000=5000m
1 min has 60 seconds hence
21 min=21*60=1260 s
Speed=5000m÷1260s=3.9682539682538 m/s
Rounded off, s=3.97 m/s
The impact speed will be
v^2 = 2*9.8*1.3
v^2 = 25.48
v= 5.04 m/s
Answer:
D- Repulsion
Explanation:
A positively charged object will exert a repulsive force upon a second positively charged object.
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)