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rosijanka [135]
2 years ago
14

An object has a kinetic energy of 810 J after falling a certain distance. If the mass of the object is 20kg, what is the speed o

f the object at this time?
I need the equation and answer please!
Physics
1 answer:
Darina [25.2K]2 years ago
6 0
Don't let the "falling" confuse you. A moving object's kinetic energy is

K.E. = 1/2 (mass) (speed^2)

no matter what direction it's moving, or why.

In this problem, you know the KE and the mass, so

810 J = 1/2 (20 kg) (speed^2).

I think you can probably find the speed now.
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Answer:

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Explanation:

A lightning conductor is made up of a sharp pointed metal (usually copper metal, as it is a very good conductor) connected directly to the ground. ... The lightning conductor is placed higher than the roof so that if lightning strikes, it strikes the conductor before it can reach the house.

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2 years ago
A person doing chin-up weighs 700.0 N, disregarding the weight of the arms. During the first 25.0 cm of the lift, each arm exert
dlinn [17]
First, we will get the resultant force:
The direction of the force due to the person's weight is vertically down.
weight of person = 700 newton

Assume that the force exerted by the arms has a vertically upwards direction.
Force exerted by arms = 2*355 = 710 newtons

Therefore, the resultant force = 710 - 700 = 10 newtons (in the vertically upwards direction) 

Now, we will get the mass of the person.
weight = 700 newtons
weight = mass * acceleration due to gravity
700 = 9.8*mass
mass = 71.428 kg

Then we will calculate the acceleration of the resultant force:
Force = mass*acceleration
10 = 71.428*acceleration
acceleration = 0.14 m/sec^2

Finally, we will use the equation of motion to get the final speed of the person.
V^2 = U^2 + 2aS where:
V is the final velocity that we need to calculate
U is the initial velocity = 0 m/sec (person starts at rest)
a is the person's acceleration = 0.14 m/sec^2
S is the distance covered = 25 cm = 0.25 meters

Substitute with the givens in the above equation to get the final speed as follows:
V^2 = U^2 + 2aS
V^2 = (0)^2 + 2(0.14)(0.25)
V^2 = 0.07
V = 0.2645 m/sec

Based on the above calculations:
The person's speed at the given point is 0.2645 m/sec

4 0
2 years ago
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2 years ago
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jenyasd209 [6]

Answer:

A

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Constant speed (without change in direction) is not accelerating. If you are slowing down, speeding up, or changing direction, you are accelerating

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Answer:

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