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A factory worker pushes a 32.0 kg crate a distance of 7.0 m along a level floor at constant velocity by pushing horizontally on

g100num [7]

Answer:

(a) 81.54 N

(b) 570.75 J

(c) - 570.75 J

(d) 0 J, 0 J

(e) 0 J

Explanation:

mass of crate, m = 32 kg

distance, s = 7 m

coefficient of friction = 0.26

(a) As it is moving with constant velocity so the force applied is equal to the friction force.

F = 0.26 x m x g = 0.26 x 32 x 9.8 = 81.54 N

(b) The work done on the crate

W = F x s = 81.54 x 7 = 570.75 J

(c) Work done by the friction

W' = - W = - 570.75 J

(d) Work done by the normal force

W'' = m g cos 90 = 0 J

Work done by the gravity

Wg = m g cos 90 = 0 J

(e) The total work done is

Wnet = W + W' + W'' + Wg = 570.75 - 570.75 + 0 = 0 J

6 0

3 years ago

Compute the dot product of the vectors u and v, and find the angle between the vectors. Bold v equals 7 Bold i minus Bold j and

OLga [1]

Answer:

$\theta = 106.3 degree$

Explanation:

As we know that

$\vec w = -\hat i + 7\hat j$

$\vec v = 7\hat i - \hat j$

also we know that

$\vec v. \vec w = -14$

it is given as

$\vec v. \vec w = (-\hat i + 7\hat j).(7\hat i - \hat j)$

$\vec v. \vec w = - 7 - 7 = -14$

also we can find the magnitude of two vectors as

$|v| = \sqrt{(-1)^2 + (7)^2}$

$|v| = \sqrt{50}$

similarly we have

$|w| = \sqrt{(7^2) + (-1)^2}$

$|w| = \sqrt{50}$

now we know the formula of dot product as

$\vec v. \vec w = |v||w| cos\theta$

$-14 = (\sqrt{50})^2cos\theta$

$\theta = cos^{-1}(\frac{-14}{50})$

$\theta = 106.3 degree$

3 0

3 years ago

The wind pushes a paper cub along the sand at a beach. The cup has a mass of 25 grams (= ? Kg's) and accelerates at a rate of 5

bixtya [17]

Force = (mass) x (acceleration)

= (0.025 kg) x (5 m/s²)

= 0.125 Newton

7 0

3 years ago

100 points! please help!!!

IRINA_888 [86]

Answer:

Explanation:

A plane flies due north (90° from east) with a velocity of 100 km/h for 2 hours.

With no wind, it will be 100*2 = 200 km north of its starting point.

But a steady wind blows southeast at 30 km/h at an angle of 315° from due east.

So the wind itself will blow the plane 30*2 = 60km at an angle of 315° from due east.

That is the same as 60*cos315° = 42.43km due east and 60*sin315° = -42.43km north.

Combining, the plane is at 42.43km due east and 200-42.43 = 157.57km due north from its starting point.

7 0

3 years ago

Read 2 more answers

A 50 kg person receives an absorbed dose of gamma radiation of 20 millirads. What is the total energy absorbed?.

Masteriza [31]

For a 50 kg person receives an absorbed dose of gamma radiation of 20 millirads, the total energy absorbed is mathematically given as

E=0.1457J

<h3>What is the total energy absorbed?</h3>

Generally, the equation for the total energy absorbed is mathematically given as

E=mass*gamma radiation

Therefore

E=50*20*19^{-3}

E=0.1457J

In conclusion, the total energy absorbed

E=0.1457J