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3 years ago

1. An object is moving in a straight line at constant speed. Which of the following is true?

Physics

1 answer:

liberstina [14]3 years ago

3 0

c. II and III only (the object has 0 acceleration and the object has constant velocity.)

Why?

Let's discard each of the given options to find the correct one(s).

<h3>- There are no forces acting on the object:</h3>

False, if an object has a constant speed, it does not mean that there are no forces acting on it, in fact, there will be always acting forces, like frictional force, gravity force, air resistance, and others.

<h3>- The object has a 0 acceleration:</h3>

True, in an object is moving at constant speed, it means that there is no acceleration, the speed will be the same all the time during motion.

<h3>- The object has constant velocity:</h3>

True, <u>if an object is moving in a straight line at constant speed</u> the velocity will be also constant. The velocity of an object is referring to its speed and its direction, if the object is moving in a straight line, the direction will be the same, so, if the speed is constant, the velocity will be also constant.

Have a nice day!

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A motorboat sets out for open sea. From home it travels 5 km due East, then heads [N35E] at 2 m/s for 90 minutes. After a break,

geniusboy [140]

The distance of the motorboat relative to the home, which travels in various directions, is 3.07 km.

<h3>What is relative velocity?</h3>

Relative velocity is a velocity of an object which is in respect to another observer, or it is a ratio of change in the position of a point to time with respect to another observer.

Given: Travel in East direction ( $d_{E}$ )= 5 km,

velocity in N35E(v) = 2 m / s, time taken(t) = 90 min = 5400 seconds,
Displacement in south ( $D_S}$ ) = 6.5 km

Firstly, find the displacement in N35E so

Displacement = Velocity × time,

$d_{NE}$ = 2 × 5400 = 10800 meters or 10.8 km

Now by using Pythagoras' theorem
We can calculate the return displacement in the south direction( $d_{S}$ ),

$d_{S}$ = $\sqrt{d^{2} _{NE}- d^{2} _{E } }$
$d_{S}$ = $\sqrt{10.8^{2}-5^{2} }$

$d_{S}$ = 9.57 km

Therefore, the distance of the boat from the home (D) = $d_S}$ - $D_S}$

D = 9.57 - 6.5;

D = 3.07 Km

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1 year ago

Two trains approach each other on parallel tracks. Each has a speed of 95 kph relative to the ground. If they are initially 8.5

aliya0001 [1]

Answer: 2.83 minutes

Explanation:

It is understood that trains are approaching. That is, they have speeds of equal magnitude but opposite. When train A travels x meters northbound, then train B travels the same distance southbound.

Therefore trains approach at a speed of:

$V = 95 +95 = 190\ km / h$

Then:

$V = \frac{x}{t}\\\\t = \frac{x}{V}$

Where x is the distance between the trains

$x = 8.5\ km$

So the time in which both trains meet is:

$t =\frac{8.5\ km}{180\ \frac{km}{h}}\\\\t=0.04722\ hours$

This is:

$0.04722*\frac{60\ minutes}{1\ hour} = 2.83\ minutes$

<em />

<em>How long will it be before they reach one another ?</em>

<h3>2.83 minutes</h3>

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3 years ago

The potential-energy function u(x) is zero in the interval 0≤x≤l and has the constant value u0 everywhere outside this interval.

VMariaS [17]

Look first for the relation between deBroglie wavelength (λ) and kinetic energy (K):
K = ½mv²
v = √(2K/m)
λ = h/(mv)
= h/(m√(2K/m))
= h/√(2Km)

So λ is proportional to 1/√K.
in the potential well the potential energy is zero, so completely the electron's energy is in the shape of kinetic energy:
K = 6U₀

Outer the potential well the potential energy is U₀, so
K = 5U₀
(because kinetic and potential energies add up to 6U₀)

Therefore, the ratio of the de Broglie wavelength of the electron in the region x>L (outside the well) to the wavelength for 0<x<L (inside the well) is:
1/√(5U₀) : 1/√(6U₀)
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4 years ago

The three stages of a train route took 1 hour ,2 hours ,and 4 hours . The first two stages were 80km and 200km of the train aver

luda_lava [24]

Answer:

the third stage was 480 km long

Explanation:

Stage 1:

Time = 1 hours

Speed = 80km

Stage 2:

Time = 2 hours