Newton's second law states that the resultant of the forces applied to an object is equal to the product between the object's mass and its acceleration:

where in our problem, m is the mass the (child+cart) and a is the acceleration of the system.
We are only concerned about what it happens on the horizontal axis, so there are two forces acting on the cart+child system: the force F of the man pushing it, and the frictional force

acting in the opposite direction. So Newton's second law can be rewritten as

or

since the frictional force is 15 N and we want to achieve an acceleration of

, we can substitute these values to find what is the force the man needs:
Answer:
<em>0.97c</em>
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Explanation:
From the relativistic equation for length contraction, we have
= 
where
is the final length of the object
is the original length of the object before contraction
β = 
where v is the speed of the object
c is the speed of light in free space = 3 x 10^8 m/s
The equation can be re-written as
/
= 
For the length to contract to one-fourth of the proper length, then
/
= 1/4
substituting into the equation, we'll have
1/4 = 
substituting for β, we'll have
1/4 = 
squaring both side of the equation, we'll have
1/16 = 1 - 
= 1 - 1/16
= 15/16
square root both sides of the equation, we have
v/c = 0.968
v = <em>0.97c</em>
Hello There!
It's a Property of matter where atoms in an object are aligned into domains
Answer:
0.76 s
Explanation:
We are given that
Length of rod,L=20 cm=
1 m=100 cm
Mass of rod,M=190 g=
Mass of ball,m=19 g=
Using 1 kg=1000g
We have to find the period if the rod and clay swing as a pendulum.
Moment of inertia of rod-clay=Moment of inertia of rod+moment of inertia of clay


Substitute the values then we get


Now, the center of mass of the combination of the rod and clay is given by

Substitute
=Distance between pivot and the center of the rod
The distance between rod and clay
Using the formula

m
Time period of the oscillation of the system of the rod and the clay is given by

g=
Using the formula
Time period=
Time-period=0.76 s
Hence, the period =0.76 s
Answer:
Coefficient of static friction = 0.547
Explanation:
The maximum resistive force offered by the body(coin)against the applied force(turntable) to continue its state of motion is called Coefficient Of Static Friction
When given
The angular velocity which is 51.1rpm
We are going to calculate velocity of coin
= r*w(angular velocity) = 0.108*(51.1*2π/60) = 0.58
Coefficient=F/N
F= coefficient* N = coefficient*m*g
F= mv^2/r which is centripetal force
Therefore, mv^2/r = coefficient*m*g
coefficient = mv^2/mgr = v^2/rg
Where g,gravity = 9.81
Substitute into the equation coefficient = 0.58^2/9.81*0.108
= 0.547