Answer:
5.88×10⁸ W
Explanation:
Power = energy / time
P = mgh / t
P = (m/t) gh
P = (1.2×10⁶ kg/s) (9.8 m/s²) (50.0 m)
P = 5.88×10⁸ W
Answer:
She can swing 1.0 m high.
Explanation:
Hi there!
The mechanical energy of Jane (ME) can be calculated by adding her gravitational potential (PE) plus her kinetic energy (KE).
The kinetic energy is calculated as follows:
KE = 1/2 · m · v²
And the potential energy:
PE = m · g · h
Where:
m = mass of Jane.
v = velocity.
g = acceleration due to gravity (9.8 m/s²).
h = height.
Then:
ME = KE + PE
Initially, Jane is running on the surface on which we assume that the gravitational potential energy of Jane is zero (the height is zero). Then:
ME = KE + PE (PE = 0)
ME = KE
ME = 1/2 · m · (4.5 m/s)²
ME = m · 10.125 m²/s²
When Jane reaches the maximum height, its velocity is zero (all the kinetic energy was converted into potential energy). Then, the mechanical energy will be:
ME = KE + PE (KE = 0)
ME = PE
ME = m · 9.8 m/s² · h
Then, equallizing both expressions of ME and solving for h:
m · 10.125 m²/s² = m · 9.8 m/s² · h
10.125 m²/s² / 9.8 m/s² = h
h = 1.0 m
She can swing 1.0 m high (if we neglect dissipative forces such as air resistance).
Find how much work ∆<em>W</em> is done by the motor in lifting the elevator:
<em>P</em> = ∆<em>W</em> / ∆<em>t</em>
where
• <em>P</em> = 45.0 kW = power provided by the motor
• ∆<em>W</em> = work done
• ∆<em>t</em> = 20.0 s = duration of time
Solve for ∆<em>W</em> :
∆<em>W</em> = <em>P</em> ∆<em>t</em> = (45.0 kW) (20.0 s) = 900 kJ
In other words, it requires 900 kJ of energy to lift the elevator and its passengers. The combined mass of the system is <em>M</em> = (<em>m</em> + 490.0) kg, where <em>m</em> is the mass of the elevator alone. Then
∆<em>W</em> = <em>M</em> <em>g h</em>
where
• <em>g</em> = 9.80 m/s² = acceleration due to gravity
• <em>h</em> = 35.0 m = distance covered by the elevator
Solve for <em>M</em>, then for <em>m</em> :
<em>M</em> = ∆<em>W</em> / (<em>g h</em>) = (900 kJ) / ((9.80 m/s²) (35.0 m)) ≈ 2623.91 kg
<em>m</em> = <em>M</em> - 490.0 kg ≈ 2133.91 kg ≈ 2130 kg
Lear vv
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greatest pressure ^^
I’m really sorry if I’m wrong
Answer:
Newton’s third law of motion states that every action has an equal and opposite reaction. This indicates that forces always act in pairs. Reaction forces are equal and opposite, but they are not balanced forces because they act on different objects so they don’t cancel each other out.
