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DanielleElmas [232]
3 years ago
7

a 1811kg car speeds up from rest when a traffic light turns green until it reaches a speed of 23m/s. how much work was done on t

he car by friction?
Physics
1 answer:
sattari [20]3 years ago
3 0

Answer:

The work done by the frictional force, W = 612565.32 J

Explanation:

Given data,

The mass of the car, m = 1811 kg

The initial velocity of the car, u = 0 m/s

The final velocity of the car, v = 23 m/s

Let the time period of the car be, t = 3 s

The acceleration of the car,

                              a = (v-u) /t

                                 = (23 - 0)/ 3

                                = 7.67 m/s²

The normal force acting on the car,

                         F = mg

                             = 1811 kg x 9.8 m/s²

                              = 17747.8 N

The displacement of the car,

                             s = ut + ½ at²

                                 = 0 + ½ x 7.67 x 3²

                                 = 54.52 m

The work done by the frictional force,

                              W = F · S

                              W = 17747.8 N x 54.52 m

                                   = 612565.32 J

Hence, the work done by the frictional force, W = 612565.32 J

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According to first equation of motion

We know that \omega =\omega _0+\alpha t , here \omega

So t=\frac{\omega -\omega _0}{\alpha }

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Mike is cutting the grass using a human-powered lawn mower. He pushes the mower with a force of 45 n directed at an angle of 41Â
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Answer:

work done will be equal to 305.05 J

Explanation:

We have given force exerted F = 45 N

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7 0
3 years ago
I will be so thankful if u answer correctly!!​
olga_2 [115]
<h2>Answer:</h2>

(a) 10N

<h2>Explanation:</h2>

The sketch of the two cases has been attached to this response.

<em>Case 1: The box is pushed by a horizontal force F making it to move with constant velocity.</em>

In this case, a frictional force F_{r} is opposing the movement of the box. As shown in the diagram, it can be deduced from Newton's law of motion that;

∑F = ma    -------------------(i)

Where;

∑F = effective force acting on the object (box)

m = mass of the object

a = acceleration of the object

∑F = F -  F_{r}

m = 50kg

a = 0   [At constant velocity, acceleration is zero]

<em>Substitute these values into equation (i) as follows;</em>

F -  F_{r} = m x a

F -  F_{r} = 50 x 0

F -  F_{r} = 0

F =  F_{r}            -------------------(ii)

<em>Case 2: The box is pushed by a horizontal force 1.5F making it to move with a constant velocity of 0.1m/s²</em>

In this case, the same frictional force F_{r} is opposing the movement of the box.

∑F = 1.5F -  F_{r}

m = 50kg

a =  0.1m/s²

<em>Substitute these values into equation (i) as follows;</em>

1.5F -  F_{r} = m x a

1.5F -  F_{r} = 50 x 0.1

1.5F -  F_{r} = 5            ---------------------(iii)

<em>Substitute </em>F_{r}<em> = F from equation (ii) into equation (iii) as follows;</em>

1.5F - F = 5            

0.5F = 5            

F = 5 / 0.5

F = 10N

Therefore, the value of F is 10N

<em />

4 0
2 years ago
Which statement is true according to Newton's first law of motion?
katrin2010 [14]
C) In the absence of an unbalanced force, an object at rest will stay at rest and an object in motion will stay in motion.

hope this helps and have a great day :)







8 0
3 years ago
Read 2 more answers
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