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SVETLANKA909090 [29]
3 years ago
10

Johnny was playing baseball with his friends and they noticed a bolt of lightning. They heard thunder seven seconds later. How f

ar away is the storm?
Physics
1 answer:
denis-greek [22]3 years ago
4 0
The storm would be at least 7 miles away cause light travels faster than sound and you can tell how many miles away a lightning bolt might have hit by how long it takes the thunder to strike<span />
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What do fossils provide evidence for?
Lapatulllka [165]

Answer:  B. the history of life in the geologic past

Explanation:

B. the history of life in the geologic past because fossils help us by telling what type of animals were alive back then ex ) a dinosaur fossil shows us what type of dinosaur it was

PLEASE MARK BRANILIEST

7 0
2 years ago
Read 2 more answers
(1 point) Which of the following statements are true?A.The equation Ax=b is referred to as a vector equation.B.If the augmented
Anvisha [2.4K]

Answer:

A. False

B. False

C. True

D. True

E. True

F. True

Explanation:

A. The equation Ax=b is referred to as a matrix equation and not vector equation.

B. If the augmented matrix [ A b ] has a pivot position in every​ row then equation Ax=b may or may not be consistent. It is inconsistent if [A b] has a pivot in the last column b and it is consistent if the matrix A has a pivot in every row.

C. In the product of Ax also called the dot product the first entry is a sum of products. For example the the product of Ax where A has [a11 a12 a13] in the first entry of each column and the corresponding entries in x are [x1 x2 x3] then the first entry in the product is the sum of products i.e.  a11x1 + a12x2 +a13x3

D. If the columns of mxn matrix A span R^m, this states that every possible vector b in R^m is a linear combination of the columns which makes the equation consistent. So the equation Ax=b has at least one solution for each b in R^m.

E. It is stated that a vector equation x1a1 + x2a2 + x3a3 + ... + xnan = b has the same solution set as that of the linear system with augmented matrix [a1 a2 ... an b]. So the solution set of linear system whose augmented matrix is [a1 a2 a3 b] is the same as solution set of Ax=b if A=[a1 a2 a3]  and b can be produced by linear combination of a1 a2 a3 iff the solution of linear system corresponding to [a1 a2 a3 b] takes place.

F.  It is true because lets say b is a vector in R^m which is not in the span of  the columns. b cannot be obtained for some x which belongs to R^m as b = Ax. So Ax=b is inconsistent for some b in R^m and has no solution.

8 0
3 years ago
Comets travel around the sun in elliptical orbits with large eccentricities. If a comet has speed 2.1×104 m/s when at a distance
trapecia [35]

Answer:

v_f = 6.92 x 10^(4) m/s

Explanation:

From conservation of energy,

E = (1/2)mv² - GmM/r

Where M is mass of sun

Thus,

E_i = E_f will give;

(1/2)mv_i² - GmM/(r_i) = (1/2)mv_f² - GmM/(r_f)

m will cancel out to give ;

(1/2)v_i² - GM/(r_i) = (1/2)v_f² - GM/(r_f)

Let's make v_f the subject;

v_f = √[(v_i)² + 2MG((1/r_f) - (1/r_i))]

G is Gravitational constant and has a value of 6.67 x 10^(-11) N.m²/kg²

Mass of sun is 1.9891 x 10^(30) kg

v_i = 2.1×10⁴ m/s

r_i = 2.5 × 10^(11) m

r_f = 4.9 × 10^(10) m

Plugging in all these values, we have;

v_f = √[(2.1×10⁴)² + 2(1.9891 x 10^(31)) (6.67 x 10^(-11))((1/(4.9 × 10^(10))) - (1/(2.5 × 10^(11)))] 20.408 e12

v_f = √[(441000000) + 2(1.9891 x 10^(30)) (6.67 x 10^(-11))((16.408 x 10^(-12))]

v_f = √[(441000000) + (435.38 x 10^(7))

v_f = 6.92 x 10^(4) m/s

5 0
4 years ago
the public is not yet able to purchase hydrogen fuel cell powered cars because engineers have to determine
grigory [225]

Answer: This would more a practical feedback than scientific.

Explanation: Despite of the protocols and processes scientists need to develop in order to stablish a new source of energy or daily life option, logistic issues are one of the most important things on the "to do list".

Would it be very expensive to acquire this kind of fuel? Is it efficient? Is it dangerous to human life or the environment? What about the negative reactions this brand new fuel could have in society?.

3 0
4 years ago
(PLEASE HELP) Which of the following describes a mixture?
enyata [817]

Answer:

D

Explanation:

3 0
3 years ago
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