Somebody help me please
1 answer:
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Answer:
0.24
Explanation:
Mass of ball= 12g=0.012Kg
height of ball= 2.5m
velocity of ball before falling= 3.2m/s
potential energy of the ball=mgh= 0.012*10*2.5=0.3J
kinetic energy of the ball=0.5*m=0.5*0.012*3.2*3.2=0.6J
Loss in mechanical energy during the fall= potential energy- Kinetic energy= 0.3-0.06=0.24J
note: During the fall, the potential energy of the ball is converted to kinetic energy. the loss in energy is due to air resistance.
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
<em><u> Moment of Man's Force is MORE : 480 N-m > 392 N-m</u></em>
<em><u> So man will be able to lift the rock.</u></em>
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
<u><em> If the Pivot is placed closer than 0.58 meters or 58 cm to the Rock, then </em></u>
<u><em> she can lift the rock.</em></u>
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
<em><u> Moment of Man's Force is MORE : 480 N-m > 392 N-m</u></em>
<em><u> So man will be able to lift the rock.</u></em>
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
<u><em> If the Pivot is placed closer than 0.58 meters or 58 cm to the Rock, then </em></u>
<u><em> she can lift the rock.</em></u>