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EastWind [94]
2 years ago
12

An electric motor takes 30 s to lift a box of mass 45 000g to a height of 1.7 m. Calculate the power of the electric motor.

Physics
1 answer:
Sidana [21]2 years ago
3 0

Power P is the amount of energy E transferred or converted per unit time t, and is expression is:

P = E/t

The necessary energy to lift the box its the work of against the Gravity Force, and is given by:

E = mgh

Then the power is:

P = E/t

P = mgh/t

P = (45 kg)(9.8 m/s²)(1.7 m )/ 30

P = 24.99 W

<h2>P ≈ 25 W</h2>
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An arrow of mass 20 g is shot horizontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth
goblinko [34]

From the question, The kinetic energy of the fired arrow is equal to the work done by the bale of hale in stopping the arrow.

We make use of the following formula

mv²/2 = F'd................... Equation 1

Where

  • m = mass of the arrow
  • v = velocity of the arrow
  • F' = average stopping force acting on the arrow
  • d = distance of penetration

Make F' the subject of the equation

F' = mv²/2d.................. Equation 2

From the question,

Given:

  • m = 20 g = 0.02 kg
  • v = 60 m/s
  • d = 40 cm = 0.4 m

Substitute these values into equation 2

  • F' = 0.02(60²)/(0.4×2)
  • F' = 72/0.8
  • F' = 90 N

Hence, The average stopping force acting on the arrow is 90 N

Learn more about average stooping force here: brainly.com/question/13370981

5 0
2 years ago
HELPPPPP !!!!
Nataly [62]

Your answer is C)

a)t=2.78 sec

b)R=835.03 m

c)

Explanation:

Given that

h= 38 m

u=300 m/s

here given that

The finally y=0

So

t=2.78 sec

The horizontal distance,R

R= u x t

R=300 x 2.78

R=835.03 m

The vertical component of velocity before the strike

4 0
2 years ago
When electrons are lost, a ( )
Tcecarenko [31]

When electrons are lost a positive ion is formed. When electrons are gained, a negative ion is formed. I hope this helps

3 0
2 years ago
A ball of clay falls freely to a concrete floor. The ball does not bounce noticeably, and it quickly comes to rest. What has hap
omeli [17]

Answer:

The mechanical energy is converted to potential energy while the kinetic energy is zero

Explanation:

mechanical energy is the sum of potential energy and kinetic energy. It is the energy associated with the motion and position of an object. The total mechanical energy is the sum of these two forms of energy.

The Law of Conservation of Energy: Energy cannot be created or destroyed, but is merely changed from one form into another. This means that potential energy can become kinetic energy, or vice versa, but energy cannot “disappear”.

The mechanical energy is converted to potential energy while the kinetic energy is zero

7 0
3 years ago
Zach, whose mass is 90 kg , is in an elevator descending at 12 m/s . the elevator takes 3.0 s to brake to a stop at the first fl
sweet-ann [11.9K]
Finding out the acceleration 12/3 = 4m/s^2
thus it is descending so the actual acceleration would be 9.8-4 = 5.8 m/s^2
the weight will be 90*5.8 = 522 N
522/9.8 = 53.2 kg
7 0
3 years ago
Read 2 more answers
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