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3 years ago

9

Can velocity of an object be negative when it’s acceleration is positive?

2 answers:

Bad White [126]3 years ago

6 0

Answer:

Yes

Explanation:

When a bike is coming to a stop the velocity is negative while the acceleration is positive.

Margaret [11]3 years ago

5 0

Answer
Yes
Example
When a car is coming to rest by braking the acceleration will be negative and the velocity will be positive.

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Which has greater kinetic energy, a car traveling at 30 km/HR or a car of half the mass traveling at 60 km/HR? a. The 60 km/HR c

artcher [175]

Answer:

a.The 60 km/HR car

Explanation:

Kinetic Energy: This can be defined as the energy of a body due to motion. The S.I unit of kinetic energy is Joules (J).

It can be expressed mathematically as

Ek = 1/2mv²......................... Equation 1

Where Ek = kinetic energy, m = mass, v = velocity.

(i) A car travelling at 30 km/hr, with a mass of m,

Ek = 1/2(m)(30)²

Ek = 450m J.

(ii) A car travelling at 60 km/hr, with a mass of m/2

Ek = 1/2(m/2)(60)²

Ek = 900m J.

Thus , the car travelling at 60 km/hr at half mass has a greater kinetic energy to the car traveling at 30 km/hr at full mass.

The right option is a.The 60 km/HR car

6 0

4 years ago

The collision and joining of crustal fragments to a continent is called continental _____.

astra-53 [7]

<h3><u>Answer;</u></h3>

Continental accretion

<h3><u>Explanation;</u></h3>

The collision and joining of crustal fragments to a continent is called the continental<em><u> </u></em><em><u>accretion</u></em><em><u>.</u></em>
<em><u>Accretion is the process through which materials such as sediment, volcanic arcs, or seamounts or blocks, etc. are added to the tectonic plate or land mass.</u></em> Many astronomical bodies, such as stars, galaxies or planets are formed by this process.

Where the process of accretion has occurred the tectonic plates may have dense basaltic rocks which are indicative of oceanic lithosphere.

3 0

3 years ago

A passenger train left station A at 6:00 p.m. Moving with the average speed 45 mph, it arrived at station B at 10:00 p.m. A tran

marishachu [46]

<h2>Average speed of transit train is 60 mph</h2>

Explanation:

Average speed of passenger train = 45 mph

Time taken from station A to station B for passenger train = 10:00 - 6:00 = 4 hours

Distance between station A to station B = 45 x 4 = 180 miles.

Time taken from station A to station B for transit train = 4 - 1 = 3 hours

Distance between station A to station B = Average speed of transit train x Time taken from station A to station B for transit train

180 = Average speed of transit train x 3

Average speed of transit train = 60 mph

Average speed of transit train is 60 mph

8 0

4 years ago

An Air Force plane lands with a velocity of 125 m/s and accelerates at a maximum rate of -6.5 m/s^2.

Alisiya [41]

Answer:

a) 19.2 s

b) No

Explanation:

Given:

v₀ = 125 m/s

a = -6.5 m/s²

v = 0 m/s

a) Find: t

v = at + v₀

(0 m/s) = (-6.5 m/s²) t + (125 m/s)

t ≈ 19.2 s

b) Find: Δx

v² = v₀² + 2aΔx

(0 m/s)² = (125 m/s)² + 2 (-6.5 m/s²) Δx

Δx ≈ 1200 m

An aircraft carrier that's 850 meters long won't be long enough.

8 0

4 years ago

The weight of spaceman Speff at the surface of planet X, solely due to its gravitational pull, is 389 N. If he moves to a distan

9966 [12]

Answer

given,

W = weight of speff at surface of planet = 384 N

h= height = 1.86 x 10⁴ Km

W' = weight of speff at height h from the planet = 24.31 N

Ms = speff mass = 75 kg

M= mass of planet = ?

R = radius of planet

G = 6.67 x 10⁻¹¹ m³/kg.s²

$g = \dfrac{W}{M}$

$g = \dfrac{389}{75}$

g = 5.187 m/s²

we know,

$g = \dfrac{GM}{r^2}$

$5.19 = \dfrac{GM}{r^2}$ .......(1)

now,

$g' = \dfrac{W}{M}$

$g' = \dfrac{24.31}{75}$

g' = 0.324 m/s²

$g = \dfrac{GM}{(r+h)^2}$

$0.324= \dfrac{GM}{(r+h)^2}$ .........(2)

dividing equation (1)/(2)

$\dfrac{5.19}{0.324}=(\dfrac{(r+h)}{r})^2$

$4=1+\dfrac{h}{r}$

$r = \dfrac{1.86\times 10^4}{3}$

r = 6.2 x 10⁶ m

mass of planet X

from equation 1

$M = \dfrac{g.r^2}{G}$

$M = \dfrac{5.19 \times (6.2\times 10^6)^2}{6.2 \times 10^{-11}}$

M = 3.21 x 10²⁴ kg

8 0

3 years ago