Answer:
D) wood rubbed against a rough surface feels hot
Explanation:
The heat is transferred from one form of energy (friction of the wood being rubbed against the surface) to another (heat energy).
Answer:
From the formula of force:

since AB and k are constants:

x is a constant of proportionality
• when force is 4N, separation distance is 1

therefore, equation becomes

when r is doubled, r becomes 2. find F:

The velocity with which the jumper leaves the floor is 5.1 m/s.
<h3>
What is the initial velocity of the jumper?</h3>
The initial velocity of the jumper or the velocity with which the jumper leaves the floor is calculated by applying the principle of conservation of energy as shown below.
Kinetic energy of the jumper at the floor = Potential energy of the jumper at the maximum height
¹/₂mv² = mgh
v² = 2gh
v = √2gh
where;
- v is the initial velocity of the jumper on the floor
- h is the maximum height reached by the jumper
- g is acceleration due to gravity
v = √(2 x 9.8 x 1.3)
v = 5.1 m/s
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For a merry go round with a radius of R=1.8 m and moment of inertia I=184 kg-m^2 is spinning with an initial angular speed of w=1.48 rad/s is mathematically given as
F= 618.9 N
<h3>What is the centripetal
force?</h3>
Generally, the equation for the angular speed is mathematically given as
w = v/R
Therefore
w= 4.7/1.8
w= 2.611 rad/s
Where total momentum
Tm= 642.96 + 272.32
Tm= 915.28
and total inertia
Ti= 184 + 246.24
Ti= 430.24
In conclusion, centripetal force
F= mrw^2
F = m*R*w2^2
F = 76*1.8*2.127^2
F= 618.9 N
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CQ
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a merry go round with a radius of R=1.8 m and moment of inertia I=184 kg-m^2 is spinning with an initial angular speed of w=1.48 rad/s in the counter clockwise direction when viewed from above a person with mass m=76 kg and velocity v=4.7 m/s runs on a path tangent to the merry go round once at the merry go round the person jumps on and holds on to the rim of the merry go round angular speed of the merry go round after the person jumps on 2.127 rad/s Once the merry go round travels at this new angular speed with what force does the person need to hold on?
Answer:
The number of free electrons per cubic meter is 
Explanation:
It is given that,
The number of free electrons per cubic meter is, 1.3
Electrical conductivity of metal, 
Density of metal, 
Atomic weight, A = 107.87 g/mol
Let n is the number of free electrons per cubic meter such that,


Where
is the density of silver atom
is the Avogadro number
A is the atomic weight of silver


or

Hence, this is the required solution.