Answer:
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(a) 1800 N
The equation of the forces along the vertical direction is:
where
is the component of the applied force along the vertical direction
N is the normal force on the sled
mg is the weight of the sled
Substituting:
F = 1210 N
m = 246 kg
We find N:
(b) 0.580
The equation of the forces along the horizontal direction is:
where
is the horizontal component of the push applied by the mule
is the static frictional force
Substituting:
F = 1210 N
N = 1800 N
We find 
, the coefficient of static friction:
(c) 522 N
In this case, the force exerted by the mule is
So now the equation of the forces along the horizontal direction can be written as
where
and 
is the new frictional force, which is different from part (b) (because the value of the force of friction ranges from zero to the maximum value 
, depending on how much force is applied in the opposite direction)
Solving the equation,
Atomic mass can change through the process of fusion. Another way is, it can also change in nuclear fusion.
The correct answer to the question is : C) Speed is the distance an object travels within a specific unit of time, whereas acceleration is the rate at which the speed or direction of an object is changing.
EXPLANATION :
Before going to answer this question, first we have to understand speed and acceleration.
The speed of a body is defined as the rate of change of distance or the distance covered by the body per unit time. Speed is scalar quantity. Hence, it needs only magnitude for its complete specification.
The acceleration produced by a body is defined as the rate of change of velocity. We know that velocity is the speed in a particular direction. Hence, the acceleration is not only produced due to the change in magnitude of velocity as well as due to the change in direction. Hence, acceleration is a vector quantity which needs magnitude as well as direction for its complete specification.
Hence, the best difference between speed and acceleration is the third statement.
