The magnitude of the force of friction is 40 N
Explanation:
To solve the problem, we just have to analyze the forces acting on the student and the scooter along the horizontal direction. We have:
- The constant pushing force forward, of magnitude F = 40 N
- The frictional force, acting backward, 
Since the two forces are in opposite direction, the equation of motion is
where
m is the mass of the student+scooter
a is the acceleration
However, here the scooter is moving at constant speed: this means that its acceleration is zero, so
a = 0
And therefore,
which means that the magnitude of the force of friction is also equal to 40 N.
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Answer:
The answer to the question is
Its maximum speed is 1.54 m/s
Explanation:
Work done = Kinetic energy
0.5·m·v² = 0.5·k·x²
Where
m = mass
v = velocity
k = spring constant
x = extension of the spring
We note that Force F is given by
F = m·a
Where
a = acceleration due to gravity
= 0.153×9.8 = 1.4994 N
Equating the work done by the force to the work done on the spring gives
Work done = Force × Distance = 1.4994×x = 0.5×k÷x² = 0.5×24.7×x²
x = 1.4994÷12.35 = 0.121 m
Substituting the value of x into the equation below gives
0.5·m·v² = 0.5·k·x²
0.5×0.153×v² = 12.35×0.121²
v² = 0.182÷0.0765 = 2.379
v = 1.54 m/s
Answer is E
time can be negative.
A is not true because <span>a=<span><span><span>d2</span>x</span><span>d<span>t2</span></span></span>=12 m/<span>s2</span></span>
C: question already said that particle move along x-axis, which is not parabola path.
D: velocity is <span><span><span>dx</span><span>dt</span></span>=12t</span>, therefore velocity changes by 12 m/s and not 9.8 m/s
So we are left with E.
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The concepts required to solve this problem are those related to the conservation of the angular momentum and the moment of inertia of the disk. We will begin by calculating the moment of inertia of the disc, then the moment of inertia of the disc after the two two blocks hits and sticks to the edges of the turn table. In the end we will apply the conservation theorem.
The radius is given as,
When a block falls from above and sticks to the turn table, the moment inertia of the turntable increases.
Since two blocks are stick to the turn table, the total final moment of inertia of the turntable is the sum moment of inertias of individual turntable, and two blocks.
The moment of inertia of each block is
Total moment of inertia of two block is
The final moment of inertia of the turn table is
From the conservation of the angular momentum, the initial angular momentum of the system is equal to final angular momentum of the system,
Rearrange the equation we have that
The magnitude of the turntable's angular velocity is 66.67rpm
