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lions [1.4K]
3 years ago
8

A football player at practice pushes a 60 kg blocking sled across the field at a constant speed. The coefficient of kinetic fric

tion between the grass and the sled is 0.30. How much force must he apply to the sled?
Physics
2 answers:
vichka [17]3 years ago
4 0

Answer:

The force must he apply to the sled is of F= 764.4 N.

Explanation:

m= 60 kg

g= 9.8 m/s²

μ=0.3

W= m*g

W= 588 N

Fr= μ*W

Fr= 176.4 N

F= W + Fr

F= 764.4 N

yuradex [85]3 years ago
3 0
<h2>Answer:</h2>

180N

<h2>Explanation:</h2>

Using Newton's law of motion;

∑F = m x a       --------------------(i)

Where;

∑F = Resultant force

m = mass of the object (sled in this case)

a = acceleration of the sled

<em>Calculate the resultant force;</em>

Since the direction of motion is horizontal, the horizontal forces acting on the sled are the;

i. Applied force (F_{A}) in one direction and;

ii. Frictional force (F_{R}) in the other direction to oppose motion

Therefore, the resultant force ∑F is the vector sum of the two forces. i.e;

∑F = F_{A} - F_{R}  -----------------------(i)

Frictional force F_{R} is the product of the coefficient of kinetic friction (μ) and weight(W) of the sled. i.e

F_{R} = μ x W

Where;

W = mass(m) x gravity(g)

W = m x g

=> F_{R} = μmg

<em>Substitute </em>F_{R}<em> into equation (ii)</em>

∑F = F_{A} - μmg

<em>Substitute ∑F into equation (i)</em>

F_{A} - μmg = ma  -------------------(iii)

Since the motion is at constant speed, it means acceleration is zero (0)

Substitute a = 0 into equation (iii) to give;

F_{A} - μmg = 0

=> F_{A} = μmg

Substitute the values of μ = 0.3, m = 60kg and g = 10m/s² into the above equation to give;

=> F_{A}  = 0.3 x 60 x 10

=> F_{A} = 180N

This means that the applied force should be 180N

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