8th grade science help help
1 answer:
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Newton's second law allows us to find that the correct answer is:
- Less than weight of the skater
Newton's second law states that the net force and is propositional to the mass and acceleration of the body
For these problems it is essential to set a reference system, with respect to which to carry out the measurements, in this case we set a coordinate system with the x axis parallel to the plane and positive in the direction of movement and the y axis perpendicular to the plane.
In the attachment we can see a free-body diagram of the problem, let's work each axis separately
x-axis
Wₓ -fr = m a
y-axis
N - = 0
N =
Where Wₓ and W_y are the components of the weight, fr the friction force that opposes the movement, m the mass and the acceleration of the body
let's use trigonometry to find the components of the weight
cos θ =
sin θ =
= W cos θ
Wₓ = W sin θ
we substitute
N = mg cos θ
From this equation we can see that the normal is less than the weight of the body.
In conclusion using Newton's second law we find that the correct answer is:
- Less than th weight of the skater
Learn more about Newton's second law here:
Answer:
<em>The force that would be applied on the rope just to start moving the wagon is 122 N</em>
Explanation:
Frictional force opposes motion between two surfaces in contact. It is the force that must be applied before a body starts to move. Static friction opposes the motion of two bodies that are in contact but are not moving. The magnitude of static friction to overcome for the body to move can be calculated using equation 1.
F = μ x mg .............................. 1
where F is the frictional force;
μ is the coefficient of friction ( μs, in this case, static friction);
m is mass of the object and;
g is the acceleration due to gravity( a constant equal to 9.81 m/)
from the equation we are provide with;
μs = 0.25
m = 50 kg
g = 9.81 m/
F =?
Using equation 1
F = 0.25 x 50 kg x 9.81 m/
F = 122.63 N
<em>Therefore a force of 122 N must be applied to the rope just to start the wagon.</em>