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3 years ago

14

A ball is thrown horizontally from a height of 19 m and hits the ground with a speed that is five times its initial speed. What

is the initial speed?

1 answer:

Helen [10]3 years ago

8 0

Answer:

The initial speed of the ball is 3.93 m/s.

Explanation:

It is given that,

A ball is thrown horizontally from a height of 19 m, h = 19 m

Let u is the initial speed of the ball so, its final velocity, v = 5u

Using third equation of motion as :

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

$(5u)^2-u^2=2\times 9.8\times 19$

$24u^2=372.4$

u = 3.93 m/s

So, the initial speed of the ball is 3.93 m/s. Hence, this is the required solution.

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A parachutist's falls to Earth is determined by two opposing forces. A gravitational force of 605 N acts on the parachutist. Aft

Juliette [100K]

Answer:

$V_f=22.596\ m/sec$

Explanation:

<u>Physics Dynamics </u>

The second Newton's Law, states the acceleration of a body will depend on the net force applied to it and its mass. If an object is left on free air the net force acting on it is the gravitational force. It will continue to fall with accelerated motion until that force is changed.

The formulas needed to compute the physics dynamics magnitudes are

$F=ma$

$V_f=V_o+at$

$W=mg$

The variables involved are: F=net force, m=mass, a=acceleration, $V_f$ = final velocity, $V_o$ = initial velocity, t = time, W = Weigh, g= $9.8\ m/sec^2$

At first, only the gravitational force of 605 N acts on the parachutist. That net force is due to the parachutist's weigh. We can know the mass

$\displaystyle m=\frac{W}{g}=\frac{605N}{9.8m/sec^2}=61,735\ kg$

If we assume the initial speed is 0, then

$V_f=gt$

All variables are assumed to be positive downwards. So, when t=3 sec

$V_f=(9.8)(3)=29.4\ m/sec$

Right then an air resistance force of 665 N appears. The new net force is

$F=605N-665N=-60N$

The new acceleration will be

$\displaystyle m=\frac{F}{m}=\frac{-60N}{61,735\ kg}=-0.972\ m/sec^2$

The acceleration is now negative since it goes upward. We are required to compute the speed after 10 sec (not clear if it's after this last event or it comes from the initial condition). We assume those 10 sec come from the very beginning of the jump, so t=7 sec

$V_f=29.4\ m/s-0.972\ m/sec^2(7\ sec)=22.596\ m/sec$

If it was t= 10\ sec

$V_f=29.4\ m/s-0.972\ m/sec^2(10\ sec)=19.68\ m/sec$

3 0

3 years ago

What is ONE variable that will change the amount of POTENTIAL ENERGY<br> of a box on the floor?

11111nata11111 [884]

Answer:

The height or the mass

Explanation:

The one variable that can change the potential energy of a box on the floor is either the height or the mass of the box.

Potential energy is the energy due to the position of a body.

Mathematically;

Potential energy = mass x acceleration due to gravity x height

Therefore, if the mass of the box is changed, the potential energy changes also.

If the position of the box is changed by raising it up, the potential energy changes

7 0

3 years ago

Determine the inductance L of a 0.65-m-long air-filled solenoid 3.2 cm in diameter containing 8400 loops.

den301095 [7]

Answer:

The inductance is $L = 0.1097 \ H$

Explanation:

From the question we are told that

The length is $l = 0.65 \ m$

The diameter is $d = 3.2 cm = 0.032 \ m$

The number of loops is $N = 8400$

Generally the radius is evaluated as

$r = \frac{ 0.032 }{2} = 0.016 \ m$

The inductance is mathematically represented as

$L = \frac{ \mu_o * N^2 * A }{ l }$

Here $\mu_o$ is the permeability of free space with value $\mu_o = 4\pi * 10^{-7} N/A^2$

A is the cross-sectional area which is mathematically evaluated as

$A = \pi r^2$

=> $A = 3.142 * (0.016)^2$

=> $A = 0.000804 \ m^2$

=> $L = \frac{ 4\pi * 10^{-7} * 8400^2 * 0.000804 }{ 0.65 }$

=> $L = 0.1097 \ H$

5 0

3 years ago

A projectile is launched from the ground at an angle of 60o above the horizontal. At what point in its trajectory does it have t

Elodia [21]

Answer:

It's constant everywhere in its trajectory.

Explanation:

the projectile was launched with an initial velocity, the only acceleration that is affecting the projectile's velocity is gravity.

The acceleration of gravity is practically equal everywhere on earth, so during its trajectory, we have to take into consideration only the acceleration because of gravity.

This is only correct because the projectile was launched with an initial velocity and it's not accelerating from rest and then falls.

5 0

3 years ago

A chemical hazard symbol means you should not inhale fumes or let the chemicals contact your skin.

pantera1 [17]

The answer is true
hope this helps : )

4 0

3 years ago