Answer:
The reason is that the value of static friction between two contact surfaces is always greater than that of the kinetic friction between the same surfaces.
Explanation:
When a body is at rest on another body, the two surfaces exert a force called static friction that prevents the surfaces from sliding.
When one of the body is in motion, the two contact surfaces exert a force between them in the direction opposite to the direction of motion is called kinetic friction. It opposes the motion of the body.
The kinetic friction acts on the surfaces only when there is a motion associated with the surface with respect to the other.
The equation for static and kinetic friction is
<em> F = μₓ · η
</em>
Both static and kinetic forces have the same dimension. Only they differ is in the value of the coefficient of friction.
On analyzing the friction between two surfaces, the static friction of the two contact surfaces is always greater than that of their kinetic friction.
Hence, it is more difficult to move an object at rest, than to keep an object moving with uniform motion.
Lab results:
Smoke detector = 40.0 cpm
Geiger counter
Americium-241 = 10,400 cpm
Geiger counter
The great difference in the radiation level means that
Americium-241 is more radioactive than the smoke detector itself. Americium-241
is used as a source of alpha radiation. This radiation ionizes the air
particles inside the smoke detector allowing it to conduct small amounts of
electric current. For example, if smoke particles go inside the smoke detector,
these are hit by alpha radiation and thus causing a drop in current. The drop
in current is detected by the smoke detector which then sets off the alarm.
Answer:
Part 1)
Part 2)
Part 3)
Part 4)
Part 5)
Explanation:
Part a)
Initial angular momentum of the merry go round is given as
here we know that
now we have
Part b)
Angular momentum of the person is given as
so we have
R = 1.99 m
so we have
Part 3)
Angular momentum of the person is always constant with respect to the axis of disc
so it is given as
Part 4)
By angular momentum conservation of the system we will have
Part 5)
Force required to hold the person is centripetal force which act towards the center
so we will have
I) Tension in the spring = 2N
ii) Angular speed of the bung=5 rads-¹
iii) The time(T) it takes to make one complete revolution=1.256 seconds
<h3>Circular motion</h3>
Formula used to calculate the time(T) it takes to make one complete revolution = 2π √(l/g)
l = radius= 40cm = 0.4m
g = acceleration due to gravity = 10m/s-²
π =3.14( constant)
T = 2× 3.14 × √0.4/10
T = 6.28 ×√0.04
T = 6.28 × 0.2
T= 1.256 seconds
Formula to calculate angular speed(w)= 2π/T
where T= 1.256 secs
Therefore w = 2×3.14/1.256
w = 6.28/ 1.256
w = 5 rads-¹
Formula to calculate Tension in the spring(F)
= mrw²
where m= 200 g = 0.2kg
r = radius= 40cm = 0.4m
w = angular speed = 5 rads-¹
Therefore F = 0.2 × 0.4 × 5²
= 0.08 ×25
= 2N
Learn more about angular speed here:
brainly.com/question/6860269