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Free_Kalibri [48]
3 years ago
7

A 53.4 kg girl is at rest on 3.55 kg skateboard. She jumps forward at 1.32 m/s. What is the velocity of the skateboard afterword

?

Physics
1 answer:
RoseWind [281]3 years ago
5 0

M = mass of the girl = 53.4 kg

m = mass of skateboard = 3.55 kg

V' = velocity of the combination of girl and skateboard before she jumps forward = 0 \frac{m }{s}

V = velocity of the girl forward = 1.32 \frac{m }{s}

v = velocity of the skateboard afterward = ?

Using conservation of momentum

(M + m) V' = MV + m v

inserting the values

(53.4 + 3.55) (0) = (53.4) (1.32) + (3.55) v

v = - 19.86 \frac{m }{s}

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A student (m = 68 kg) falls freely from rest and strikes the ground. During the collision with the ground, he comes to rest in a
Gnesinka [82]

Answer:

5.7141 m

Explanation:

Here the potential and kinetic energy will balance each other

mgh=\frac{1}{2}mv^2\\\Rightarrow v=\sqrt{2gh}

This is the initial velocity of the system and the final velocity is 0

t = Time taken = 0.04 seconds

F = Force = 18000 N

a = Acceleration

g = Acceleration due to gravity = 9.81 m/s²

Equation of motion

v=u+at\\\Rightarrow a=\frac{v-u}{t}

From Newton's second law

F=ma\\\Rightarrow F=m\frac{v-u}{t}\\\Rightarrow 18000=68\frac{0-\sqrt{2gh}}{0.04}\\\Rightarrow \frac{18000}{68}\times 0.04=-\sqrt{2\times 9.81\times h}\\\Rightarrow 10.58823=-\sqrt{2\times 9.81\times h}

Squarring both sides

112.11061=2\times 9.81\times h\\\Rightarrow h=\frac{112.11061}{2\times 9.81}\\\Rightarrow h=5.7141\ m

The height from which the student fell is 5.7141 m

5 0
3 years ago
The first PCS technology used a form of time division multiplexing called ____.​ a. ​Time Division Multiple Access (TDMA) b. ​Gl
salantis [7]

Answer:

A. Time Division multiple Access (TDMA)

Explanation:

Time-division multiple access (TDMA) is a channel access method for shared-medium networks

It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot.

3 0
3 years ago
An 800 kg fishing boat going south at 12 m/s runs into a stopped pontoon boat (1400 kg). The boats stick together and move south
kykrilka [37]

Answer:

the velocity of the boats after the collision is 4.36 m/s.

Explanation:

Given;

mass of fish, m₁ = 800 kg

mass of boat, m₂ = 1400 kg

initial velocity of the fish, u₁ = 12 m/s

initial velocity of the boat, u₂ = 0

let the final velocity of the fish-boat after collision = v

Apply the principle of conservation of linear momentum for inelastic collision;

m₁u₁ + m₂u₂ = v(m₁ + m₂)

800 x 12    +   1400 x 0 = v(800 + 1400)

9600 = 2200v

v = 9600/2200

v = 4.36 m/s

Therefore, the velocity of the boats after the collision is 4.36 m/s.

7 0
3 years ago
A boat has a propulsion system that consists of a pump that sucks water at the bow and presses it on the stern. All tubes are 5
Phoenix [80]

Answer:

The propulsion force at the moment of departure, is 49 N  

Explanation:

Given;

diameter of tubes = 5 cm = 0.05 m

volumetric flow rate, V = 50 L/s = 0.005 m³/s

density of water, ρ = 1000 Kg /m³

hydraulic / propulsion force, F = ρVg

where;

ρ is the density of the fluid (water)

V is the volumetric flow rate of water

g is acceleration due to gravity

propulsion force, F = ρVg

propulsion force, F = 1000 x 0.005 x 9.8

propulsion force, F = 49 N      

Therefore, the propulsion force at the moment of departure, is 49 N  

7 0
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Please Help! The thing is in the photo.
ivolga24 [154]

The reaction 4Al + 3O₂ → 2Al₂O₃ is a synthesis or also called combination reaction because reactants combine to produce a new compound (Option 2).

<h3>What is a synthesis combination reaction?</h3>

In chemistry, a synthesis or combination reaction is any type of chemical reaction in which two or more molecules called reactants combine to produce one or more molecules called products of such reaction.

Therefore, with this data, we can see that a synthesis or combination reaction is a chemical process where two or more molecules combine to produce a new molecule known as a product.

Learn more about synthesis combination reactions here:

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