Ask question

Ask question

All categories

4 years ago

15

A ball is thrown upwards and returns to the same location. Compared with its initial speed its speed when it returns is about___

_____________.

1 answer:

Strike441 [17]4 years ago

4 0

Answer:

Explanation:

Let the ball is thrown upwards with speed u and reaches upto height h.

Use III equation of motion

$v^{2}=u^{2}-2gh$

here, final velocity v = 0

So, $u = \sqrt{2gh}$

Now as the ball reaches the maximum height, it starts falling freely. Let it strkes with the ground with velocity v'.

$v'^{2}=u^{2}-2gh$

here, u = 0

So, $v' = \sqrt{2gh}$

It means the velocity is same as the velocity of projection.

You might be interested in

A heavy solid disk rotating freely and slowed only by friction applied at its outer edge takes 120 seconds to come to a stop.

alisha [4.7K]

Answer:

The time is 16 min.

Explanation:

Given that,

Time = 120 sec

We need to calculate the moment of inertia

Using formula of moment of inertia

$I=\dfrac{1}{2}MR^2$

If the disk had twice the radius and twice the mass

The new moment of inertia

$I'=\dfrac{1}{2}\times2M\times(2R)^2$

$I'=8I$

We know,

The torque is

$\tau=F\times R$

We need to calculate the initial rotation acceleration

Using formula of acceleration

$\alpha=\dfrac{\tau}{I}$

Put the value in to the formula

$\alpha=\dfrac{F\times R}{\dfrac{1}{2}MR^2}$

$\alpha=\dfrac{2F}{MR}$

We need to calculate the new rotation acceleration

Using formula of acceleration

$\alpha'=\dfrac{\tau}{I'}$

Put the value in to the formula

$\alpha=\dfrac{F\times R}{8\times\dfrac{1}{2}MR^2}$

$\alpha=\dfrac{2F}{8MR}$

$\alpha=\dfrac{\alpha}{8}$

Rotation speed is same.

We need to calculate the time

Using formula angular velocity

$\Omega=\omega'$

$\alpha\time t=\alpha'\times t'$

Put the value into the formula

$\alpha\times120=\dfrac{\alpha}{8}\times t'$

$t'=960\ sec$

$t'=16\ min$

Hence, The time is 16 min.

5 0

3 years ago

An object possessing an excess of 6.0x10^6 electrons has a net charge of

guajiro [1.7K]

A single electron has a charge of
$e=-1.6 \cdot 10^{19}C$
Therefore, if we have an excess of $N=6.0\cdot10^6$ electrons, the total net charge will be the product between the charge of a single electron and the total number of electrons in excess:
$Q=Ne=(6.0\cdot10^6)(-1.6 \cdot 10^{-19}C)=9.6 \cdot 10^{-13}C$

7 0

3 years ago

An electron in a mercury atom changes from energy level b to a higher energy level when the

emmainna [20.7K]

The energy is 3.06 electronvolts, E = 3.06eV

1eV = 1.6 * 10^-19 J

3.06 eV = 3.06* 1.6 * 10^-19 J = 4.896 * 10^-19 J

4 0

3 years ago

If humans originated in Africa and migrated to other parts of the world some time would be required for this to occur.At the mod

Thepotemich [5.8K]

Answer:

100 years

Explanation:

10,000 divided by 100 equals 100

7 0

3 years ago

During a firework display, a shell is shot through the air with an initiak speed of 70 m/s at an angle of 75° above the horizont

ladessa [460]

Answer:

241.24m

Explanation:

The height at which the shell explodes will be at the maximum height. In projectile motion, maximum height formula is expressed as:

H = u²sin²θ/2g

u is the initial speed = 70m/s

θ the angle of launch = 75°

g is the acceleration due to gravity = 9.81m/s²

Substitute the values into the formula and get H

H = 70²(sin75°)/2(9.81)

H = 4900sin75°/19.62

H = 4900*0.9659/19.62

H = 4733.037/19.62

H = 241.24m

Hence the height at which the shell explodes is 241.24m

4 0

3 years ago