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soldi70 [24.7K]

2 years ago

7

Two ice skaters, Lilly and John, face each other while stationary and push against each others hands. John's mass is twice the m

ass of Lilly. How do their speeds compare after the push offs?

1 answer:

VladimirAG [237]2 years ago

7 0

Answer:

lily's speed would be twice john's speed

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Fill in the blanks to complete the statements.

Murljashka [212]

Answer:

When an object changes speed (increases/decreases) it results in acceleration/de acceleration, its velocity also changes.

Explanation:

Acceleration is the rate of change in velocity.An object can accelerate when speed increases, decreases or direction changes. All these instances involves a change in velocity.Velocity is a vector quantity thus it has magnitude and the direction.Acceleration due to change in direction is centripetal acceleration.The expression for finding acceleration is;

a=change in velocity/change in time

a=Δv/Δt in m/s²

3 0

2 years ago

Platinum has a density of 21.4 g/cm3. if thieves were to steal platinum from a bank using a small truck with a maximum payload o

slega [8]

We will convert the 1dm3 in terms of cm3 as follows:

1dm^3 = (10 cm)^3
= 1000 cm^3

The mass of platinum is equal to 900 lb.
Then we will convert the mass in terms of grams as follows:
1 lb = 453.6 g
900 = 900 x 453.6 g
= 408240 g

Then density of platinum is equal to 21.4 g/cm^3
We will calculate the volume of platinum in mass 408240 g as follows:
Volume of platinum = mass of platinum / density of platinum
= 408240 g / 21.4 g/cm^3
= 19076.6 cm^3

The total volume of platinum is 19076.6 cm^3
The volume of platinum in 1 L bar is 1000cm^3
So, to calculate the number of bars we will use the formula as follows;
Number of bars = volume of platinum available / volume of platinum required in 1 L bar
= 19076.6 cm^3 / 1000 cm^3
= 19
So, the number of bars are 19.

4 0

2 years ago

a graph compares the weight and height of several different breeds of cat. What type of model is the graph?

pickupchik [31]

Answer: Mathematical Model

Explanation:

Took the test

3 0

2 years ago

Lightning bolts can carry currents up to approximately 20 kA. We can model such a current as the equivalent of a very long, stra

ioda

Given Information:

Current due to Lightning bolt = I₁ = 20 kA

Current of household = I₂ = 10 A

Distance = r₁ = 4.9 m

Distance = r₂ = 4.9 cm = 0.049 m

Required Information:

a) Magnetic field due Lightning bolt = B₁ = ?

b) Magnetic field due to household current = B₂ = ?

Answer:

a) Magnetic field due Lightning bolt = B₁ = 8.16×10⁻⁴ T

b) Magnetic field due to household current = B₂ = 4.08×10⁻⁵ T

B₁ = 20B₂

Explanation:

The magnetic field produced in a long straight wire carrying a current (I) at distance r is given by

B = μ₀I/2πr

Where μ₀ is the permeability of free space and its value is 4π×10⁻⁷

a) The magnetic field produced due to the lightning bolt current is

B₁ = μ₀I₁/2πr₁

B₁ = (4π×10⁻⁷*20,000)/2π*4.9

B₁ = 0.000816

B₁ = 8.16×10⁻⁴ T

Therefore, the strength of magnetic field due to the lightning bolt current is 8.16×10⁻⁴ T

b) The magnetic field produced due to the household current is

B₂ = μ₀I₂/2πr₂

B₂ = (4π×10⁻⁷*10)/2π*0.049

B₂ = 0.00004081

B₂ = 4.08×10⁻⁵ T

Therefore, the strength of magnetic field due to the household current is 4.08×10⁻⁵ T

The ratio of magnetic field produced by the lightning bolt current to the magnetic field produced by the household current is

B₁/B₂ = 8.16×10⁻⁴/4.08×10⁻⁵

B₁/B₂ = 20

B₁ = 20B₂

Which means that the magnetic field produced by the lightning bolt current is 20 time greater than the magnetic field produced by the household current.

6 0

2 years ago

A small rock is thrown vertically upward with a speed of 22.0 m/s from the edge of the roof of a 30.0-m-tall building. The rock

RSB [31]

To solve this problem we will apply the kinematic equations of linear movement. For this purpose we will begin to define the final speed of the body before hitting the street. The first equation will begin using the difference in velocities as a function of acceleration (gravity) and position. And the second will use the concept of acceleration, time and speed, to find the time variable.

PART A) Equation of motion is

$v^2-u^2 = 2as$

$v^2 = u^2+2as$

Replacing,

$v^2 = 22^2+2(9.8)(30)$

$v = 32.74m/s$

The speed of rock before hitting the ground is 32.74m/s

PART B) Equation of motion

$v-u=at$

$t = \frac{v-u}{a}$

$t = \frac{32.74-(-22)}{9.8}$

$t = 5.58s$

Therefore the time taken by the rock is 5.58s

4 0

2 years ago