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4 years ago

A ball is thrown with an initial upward velocity of 5 m/s.

Physics

1 answer:

miv72 [106K]4 years ago

6 0

Answer:

A ball is thrown at an initial height of 5 feet with an initial upward velocity at 29 ft/s. lets assume that balls height h (in feet) after t seconds is give by:

Explanation:

h= 5 + 29t -16t^2

a time when the ball's height will be 17 ft

17 = 5 + 29t -16t2

0 = -17 + 5 + 29t -16t2

0 = -12 + 29t - 16t2

Using the quadratic equation:

t = (-29±√(292-(4*(-16)*(-12))))÷2(-16)

= (-29±√(841 - 768))÷(-32)

= (-29±√(73))÷(-32)

= (-29 + 8.544)÷(-32) or (-29 - 8.544)÷(-32)

= (-20.456)÷(-32) or -37.544÷(-32)

= 0.64 or 1.17

So, the ball is at a height of 17 ft twice: once on the way up after 0.64 seconds and once on the way back down after 1.17 seconds.

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6000 kg train moving 5 m/sec to east collides with 5000 kg train moving 3 m/sec to west. What is their velocity

Svetlanka [38]

The final velocity is 1.37 m/s east

Explanation:

We can solve this problem by using the law of conservation of momentum: in fact, in absence of external forces, the total momentum of the two trains must be conserved before and after the collision.

So we can write:

$p_i = p_f\\m_1 u_1 + m_2 u_2 = (m_1+m_2)v$

where:

$m_1 = 6000 kg$ is the mass of the first train

$u_1 = 5 m/s$ is the initial velocity of the first train (we take east as positive direction)

$m_2 = 5000 kg$ is the mass of the second train

$u_2 = -3 m/s$ is the initial velocity of the second train

$v$ is the final combined velocity of the two trains

Re-arranging the equation and substituting the values, we find:

$v=\frac{m_1 u_1 + m_2 u_2}{m_1+m_2}=\frac{(6000)(5)+(5000)(-3)}{6000+5000}=1.37 m/s$

And the positive sign indicates their final direction is east.

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3 years ago

Calculate the kinetic energy of an 80,000 kg airplane that is flying with a velocity of 167 m/s.

liq [111]

Answer:

1115560000 J

Explanation:

1/2 * 80,000 * 167^2 m/s = 1115560000 J

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3 years ago

What is nuclear fission? why is this process important to stars?

KIM [24]

Nuclear fusion is a reaction in which two or more atomic nuclei come very close and then collide at a very high speed and join to form a new nucleus. This process is important to stars because they get their energy from the nuclear fusion process

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4 years ago

A 10.0-kg box starts at rest on a level floor. An external, horizontal force of 2.00 × 102 N is applied to the box for a distanc

Harman [31]

Answer:

vf = 11.2 m/s

Explanation:

m = 10 Kg

F = 2*10² N

x = 4.00 m

μ = 0.44

vi = 0 m/s

vf = ?

We can apply Newton's 2nd Law

∑ Fx = m*a (→)

F - Ffriction = m*a ⇒ F - (μ*N) = F - (μ*m*g) = m*a ⇒ a = (F - μ*m*g)/m

⇒ a = (2*10² N - 0.44*10 Kg*9.81 m/s²)/10 Kg = 15.6836 m/s²

then , we use the equation

vf² = vi² + 2*a*x ⇒ vf = √(vi² + 2*a*x)

⇒ vf = √((0)² + 2*(15.6836 m/s²)*(4.00m)) = 11.2 m/s

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3 years ago

A 75-kg piano is hoisted on a crane and delivered throughout the window of a 6th story apartment (20 meters above ground). What

ipn [44]

Answer:

P = 14700 J

Explanation:

Given that,

Mass of a piano, m = 75 kg

It is delivered throughout the window of a 6th story apartment which is 20 m above the ground.

We need to find the potential energy of the piano. It is given by :

P = mgh

Putting all the values,

P = 75 kg × 9.8 m/s² × 20 m

P = 14700 J

So, the potential energy of the piano is 14700 J.

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3 years ago