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3 years ago

A man plans to use a 2 metre crowbar to lift a rock by putting a pivot 0,8 m from

Physics

2 answers:

miv72 [106K]3 years ago

6 0

The answer is 0.58 meters. I agree with the working shown below. I did the same on paper, and it is the right answer.

sp2606 [1]3 years ago

4 0

1. The man will be able to move the rock. See diagram.
 Moment of Man's force : 400 N * 1.2 meter = 480 N-m
 Rock's Weight = 50 Kg * 9.8 m/sec² = 490 Newtons
 Moment of Rock's weight : 490 N * 0.80 meters = 392 N-m

  Moment of Man's Force is MORE : 480 N-m > 392 N-m
 So man will be able to lift the rock.

2. Let is look at the diagram - second one.
 Let us assume that the fulcrum (Pivot) is placed at X meters from the rock.
 So moment of Girl's force about Pivot = 200 N * (2 - X) meters = 400 - 200 X
 Moment of Rock's weight = 490 N * X = 490 X

 As the Girl is able to lift the rock, 400 - 200 X > 490 X
 Hence 400 > 200 X + 490 X
 400 > 690 X
 X < 400/690 = 0.58 meters
  If the Pivot is placed closer than 0.58 meters or 58 cm to the Rock, then 
 she can lift the rock.

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3. A pendulum with a 1.0-kg weight is set in motion from a position 0.04 m above the lowest point on the path of the weight.

gavmur [86]

Answer: K.E = 0.4 J

Explanation:

Given that:

M = 1.0 kg

h = 0.04 m

K.E = ?

According to conservative of energy

K.E = P.E

K.E = mgh

K.E = 1 × 9.81 × 0.04

K.E = 0.3924 Joule

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6 0

3 years ago

A ship travels with velocity given by 12, with current flowing in the direction given by 11 with respect to some co-ordinate axe

nataly862011 [7]

Answer:

$v_x = 11.78 m/s$

Explanation:

Velocity of the ship is given as

$v = 12 units$

the direction of the velocity of the ship is making an angle of 11 degree with the current

so we will have two components of the velocity

1) along the direction of the current

2) perpendicular to the direction of the current

so here we know that the component of the ship velocity along the direction of the current is given as

$v_x = v cos\theta$

$v_x = 12 cos11$

$v_x = 11.78 m/s$

7 0

3 years ago

Question 1 (1 point)

deff fn [24]

Answer:

Travelled 18 km, they are 6 km from home.

Explanation:

12/2 (halfway) is 6km. So, 6 + 12 would be 18 km, total amount travelled. The total distance of the trip would be 24 km (12 km out, 12km back) if they travelled 12+6 (18km) then they only have 6 km more to go.

5 0

3 years ago

A farsighted boy has a near point at 2.3 m and requires eyeglasses to correct his vision. Corrective lenses are available in inc

tino4ka555 [31]

Answer:

P = 3.5 D

Explanation:

As we know that convex lens is to be used to make the near point of eye to be correct

So we will have

$\frac{1}{d_i} + \frac{1}{d_o} = \frac{1}{f}$