Which is one way that scientists ensure that data is reliable?

A group of students prepare for a robotic competition and build a robot that can launch large spheres of mass M in the horizonta

jeyben [28]

Answer:

$V_0$

Explanation:

Given that, the range covered by the sphere, $M$ , when released by the robot from the height, $H$ , with the horizontal speed $V_0$ is $D$ as shown in the figure.

The initial velocity in the vertical direction is $0$ .

Let $g$ be the acceleration due to gravity, which always acts vertically downwards, so, it will not change the horizontal direction of the speed, i.e. $V_0$ will remain constant throughout the projectile motion.

So, if the time of flight is $t$ , then

$D=V_0t\; \cdots (i)$

Now, from the equation of motion

$s=ut+\frac 1 2 at^2\;\cdots (ii)$

Where $s$ is the displacement is the direction of force, $u$ is the initial velocity, $a$ is the constant acceleration and $t$ is time.

Here, $s= -H, u=0,$ and $a=-g$ (negative sign is for taking the sigh convention positive in $+y$ direction as shown in the figure.)

So, from equation (ii),

$-H=0\times t +\frac 1 2 (-g)t^2$

$\Rightarrow H=\frac 1 2 gt^2$

$\Rightarrow t=\sqrt {\frac {2H}{g}}\;\cdots (iii)$

Similarly, for the launched height $2H$ , the new time of flight, $t'$ , is

$t'=\sqrt {\frac {4H}{g}}$

From equation (iii), we have

$\Rightarrow t'=\sqrt 2 t\;\cdots (iv)$

Now, the spheres may be launched at speed $V_0$ or $2V_0$ .

Let, the distance covered in the $x-$ direction be $D_1$ for $V_0$ and $D_2$ for $2V_0$ , we have

$D_1=V_0t'$

$D_1=V_0\times \sqrt 2 t$ [from equation (iv)]

$\Rightarrow D_1=\sqrt 2 D$ [from equation (i)]

$\Rightarrow D_1=1.41 D$ (approximately)

This is in the $3$ points range as given in the figure.

Similarly, $D_2=2V_0t'$

$D_2=2V_0\times \sqrt 2 t$ [from equation (iv)]

$\Rightarrow D_2=2\sqrt 2 D$ [from equation (i)]

$\Rightarrow D_2=2.82 D$ (approximately)

This is out of range, so there is no point for $2V_0$ .

Hence, students must choose the speed $V_0$ to launch the sphere to get the maximum number of points.

7 0

3 years ago

Lenz's Law: A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field va

julia-pushkina [17]

Answer:

Explanation:

The magnetic field is straight up. It is reducing . As per Lenz's law , direction of induced current is such that it opposes the reason which creates it . magnetic field in upper direction is reducing . So current will be such that magnetic field produced by it increases magnetic field in upper direction . In other words , induced current should create magnetic field in upward direction. It is possible when direction of induced current is anti - clockwise, when seen from above.

5 0

3 years ago

Coherent microwaves of wavelength 5.00 cm enter a tall, narrow window in a building otherwise essentially opaque to the microwav

zzz [600]

The solution for this problem is:

For 1st minimum, let m be equal to 1.

d = slit width

D = screen distance.

Θ = arcsin (m * lambda/ (d))

= 0.13934 rad, 7.9836 deg

y = D*tan (Θ)

y = 6.50 * tan (7.9836)

= 0.91161 m is the distance from the central maximum to the first-order minimum

8 0

3 years ago

A student is preparing to bake a cake at home and places several ingredients on the countertop to use. First he preheats the ove

Evgen [1.6K]

Answer:

baking the cake batter

Explanation:

Baking the cake batter will indicate that chemical change has occurred here. What is a chemical change?

A chemical change is one in which a new kind of matter is formed.
It is usually accompanied by energy either evolution or absorption of energy in form of heat or light or both.
The process is irreversible.
When the batter bakes, a new substance different from the cake mix is obtainable.
We cannot get back the ingredient from this baked cake. It is impossible.
This is good indicator of chemical change.

7 0

3 years ago

Use the graph below to answer the following question: if average acceleration is calculated using the equation, “ change in velo

sergiy2304 [10]

Answer:

$a=9\ cm/s^2$

Explanation:

<u>Average Acceleration </u>

Acceleration is a physical magnitude defined as the change of velocity over time. When we have experimental data, we can compute it by calculating the slope of the line in velocity vs time graph.

Note: <em>We cannot see if the time axis is numbered in increments of 1 second, and we'll assume that. </em>

When $t_2=4\ sec$ , the graph shows a value of $v_2=36\ cm/s$