How long does it take for the ball to hit the wall?<br> At what height does the ball hit the wall?

A 28 g bullet pierces a sand bag 29 cm thick. If the initial bullet velocity was 55 m/s and it emerged from the sandbag with 18

Bumek [7]

The correct answer to the question is 130.4 N.

CALCULATION;

The mass of the bullet is given as m = 28 gram = 0. 028 kg.

The initial velocity of the bullet u = 55 m/s

The final velocity of the bullet v = 18 m/s.

The distance covered by the bullet through the sand bag s = 29 cm.

= 0.29 m

Let the acceleration of the bullet is a .

From equation of kinematics, we know that-

$v^2-u^2=\ 2as$

⇒ $a=\ \frac{v^2-u^2}{2s}$

$=\ \frac{(18)^2-(55)^2}{2\times 0.29}\ m/s^2$

$=\ -4656.897\ m/s^2$

The negative sign is used due to the fact that force is opposing in nature. Its velocity is decreasing with time.

From Newton's second law of motion, we know that net force on a body is equal to the product of mass with acceleration.

Mathematically F = ma.

Hence, the frictional force exerted on the bullet is calculated as -

F = m × a

= 0.028 × (-4656.897) N

= -130.4 N [ANS]

Here, N ( newton) stands for the unit of force.

8 0

3 years ago

Why can a bowling ball do work

Karo-lina-s [1.5K]

it cant beacuse its not a person

8 0

3 years ago

The height of a cone is increasing at a rate of 10 cm/sec and its radius is decreasing so that its volume remains constant. How

ki77a [65]

Answer:

dr/dt = -2 cm/s.

Explanation:

The volume of a cone is given by:

$V=\frac{1}{3} \pi r^{2}h$ (1)

r is the radius
h is the height

Let's take the derivative with respect to time in each side of (1).

$\frac{dV}{dt}=\frac{1}{3} \pi \frac{d}{dt}(r^{2}h)=\frac{1}{3} \pi \left(2r\frac{dr}{dt}h+r^{2}\frac{dh}{dt} \right)$ (2)

We know that:

dh/dt = 10 cm / s (rate increasing of height)
dV/dt = 0 (constant volume means no variation with respect of time)
r = 4 cm
h = 10 cm

We can calculate how fast is the radius changing using the above information.

$0=\frac{1}{3} \pi \left( 2\cdot 4\cdot \frac{dr}{dt} \cdot 10 + 4^{2}\cdot 10)\right$

Therefore dr/dt will be:

$\frac{dr}{dt}=-\frac{160}{80}=-2 cm/s$

The minus signs means that r is decreasing.

I hope it helps you!

6 0

3 years ago

Electrons are (2 points)

ddd [48]

<span>electrons are able to move from one atom to another; the atom that loses an electron becomes positively charged and the atom that gains an electron becomes negatively charged.</span>

3 0

4 years ago

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According to the Biot-Savart Force Law and the right hand rule, if a magnetic field is directed rightward (+ x axis) and a posit

julsineya [31]

The direction would go upwards(+yaxis)

6 0

4 years ago

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How long does it take for the ball to hit the wall? At what height does the ball hit the wall?