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3 years ago

Which statement is true?

Physics

1 answer:

Jet001 [13]3 years ago

6 0

Answer:

A. Speed is a scalar quantity and velocity is a vector quantity.

Explanation:

A scalar quantity is one that consists of only a numerical value.

Speed is a scalar quantity because only the instantaneous value is indicated, for example the speedometer of a car that tells you your speed at the moment but not where you are going or in what direction are you going.

On the other hand, velocity is a vector quantity. Because it is composed of a <u>magnitude and a direction</u>, for example 10m/s to the south is a velocity, and 10m/s is a speed.

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Alan hits a hockey pick of mass 0.3 kg across a hockey rink with a velocity of 18 m/s to the east.

Talja [164]

PART a)

Momentum is defined as product of mass and velocity

so here initial momentum is

$P = mv$

given that

m = 0.3 kg

v = 18 m/s

$P = 0.3(18) = 5.4 kg m/s$

towards East

Part b)

Since puck was initially at rest so here initial momentum must be ZERO

so here to find the force we can use

$F = \frac{\Delta P}{\Delta t}$

so here we have

time interval = 0.25 s

now from above equation

$F = \frac{5.4 - 0}{0.25}$

$F = 21.6 N$

Part c)

Due to friction the puck lose its speed by 5 m/s

final speed = 18 - 5 = 13 m/s

mass = 0.3 kg

final momentum = (0.3)(13) = 3.9 kg m/s

now the impulse due to friction force is given as

$Impulse = P_f - P_i$

$impulse = 3.9 - 5.4 = -1.5 kg m/s$

Part d)

initial momentum of block will be ZERO as it is placed at rest

Initial momentum of the puck is given as

$P = mv = (0.3)(13) = 3.9 kg m/s$

so total momentum before collision is given as

$P = 3.9 + 0 = 3.9 kg m/s$

Part e)

since the system is isolated and there is no external force on it

So here momentum will remain conserved

so here we have

$P_i = P_f$

$3.9 = (m_1 + m_2) v$

$3.9 = (0.3 + 1.2)v$

$v = 2.6 m/s$

so final combined speed will be 2.6 m/s

8 0

3 years ago

Read 2 more answers

A 500.0-g chunk of an unknown metal, which has been in boiling water for several minutes, is quickly dropped into an insulating

mixas84 [53]

Answer:

electeicity is caused by the movement of. from one atom to the next

6 0

3 years ago

A ball that is attached to a string travels in a horizontal, circular path, as shown in Figure 1. At time t0 , the ball has a sp

Levart [38]

Answer:

F₁ = 4 F₀

Explanation:

The force applied on the string by the ball attached to it, while in circular motion will be equal to the centripetal force. Therefore, at time t₀, the force on ball F₀ is given as:

F₀ = mv₀²/r --------------- equation (1)

where,

F₀ = Force on string at t₀

m = mass of ball

v₀ = speed of ball at t₀

r = radius of circular path

Now, at time t₁:

v₁ = 2v₀

F₁ = mv₁²/r

F₁ = m(2v₀)²/r

F₁ = 4 mv₀²/r

using equation (1):

5 0

3 years ago

Sound wave frequency difference

motikmotik

Are u trying to ask what the difference between a sound wave and a frequency is?

6 0

3 years ago

Three pendulums with strings of the same length and bobs of the same mass are pulled out to angles θ1, θ2, and θ3, respectively,

seropon [69]

Answer:

The angular frequencies of all the 3 pendulums shall be same.

Explanation:

The time period of a simple pendulum with the approximation $sin(\theta )\approx \theta$ is given by:

$T=2\pi\sqrt{\frac{l}{g}}$

The angular frequency $\omega$ is given by

$\omega =\frac{2\pi }{T}\\\\\omega =\frac{2\pi}{2\pi \sqrt{\frac{l}{g}}}\\\\\therefore \omega =\sqrt{\frac{g}{l}}$

As we can see that the angular frequency is independent on the initial angle (valid strictly for small angle approximations) we conclude that the angular frequencies of the 3 pendulums are the same.

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4 years ago