Answer:
Calculating Coefficient of friction is 0.229.
Force is 4.5 N that keep the block moving at a constant speed.
Explanation:
We know that speed expression is as
.
Where,
is initial speed, V is final speed, ∆s displacement and a acceleration.
Given that,
=3 m/s, V = 0 m/s, and ∆s = 2 m
Substitute the values in the above formula,

0 = 9 - 4a
4a = 9

is the acceleration.
Calculating Coefficient of friction:


Compare the above equation

Cancel "m" common term in both L.H.S and R.H.S





Hence coefficient of friction is 0.229.
calculating force:


F = 4.5 N
Therefore, the force would be <u>4.5 N</u> to keep the block moving at a constant speed across the floor.
Kepler's second law of planetary motion<span> describes the speed of a </span>planet<span> traveling in an elliptical orbit around the sun. It states that a line between the sun and the </span>planetsweeps equal areas in equal times. Thus, the speed of theplanet<span> increases as it nears the sun and decreases as it recedes from the sun.</span>
Power = work/time
P = 105J/103s
P = <span>1.019 watts</span>
Answer:
The required angular speed ω of an ultra-centrifuge is:
ω = 18074 rad/sec
Explanation:
Given that:
Radius = r = 1.8 cm
Acceleration due to g = a = 6.0 x 10⁵ g
Sol:
We know that
Angular Acceleration = Angular Radius x Speed²
a = r x ω ²
Putting the values
6 x 10⁵ g = 1.8 cm x ω ²
Converting 1.8 cm to 0.018 m, also g = 9.8 ms⁻²
6 x 10⁵ x 9.8 = 0.018 x ω ²
ω ² = (6 x 10⁵ x 9.8) / 0.018
ω ² = 5880000 / 0.018
ω ² = 326666667
ω = 18074 rad/sec