All categories

4 years ago

Is the acceleration due to gravity in projectile motion always negative? please explain

1 answer:

3 0

Before you start working on any motion problem, YOU decide which direction you're going to call 'positive'. Everybody almost always calls UP positive, and the acceleration of gravity points down, so it winds up negative. But you could just as well call DOWN the positive direction. Then, the cannonball is fired with a negative vertical speed, and the acceleration of gravity eventually robs all of its negative speed, and makes it start falling in the positive direction. The whole thing is your choice.

You might be interested in

1.) an object moves along the x axis, subject to the potential energy shown. The object has a mass of 1.1kg and starts at rest a

MrRa [10]

If I'm not wrong #1 should be C

4 0

4 years ago

The "Garbage Project" at the University of Arizona reports that the amount of paper discarded by households per week is normally

Lorico [155]

Answer:

54%

Explanation:

We are given that

S.D=4.2 lb

Mean= $\mu=9.4 lb$

We have to find the percentage of household throw out at least 9 lb of paper a week.

Normal distribution formula :

$P(X\geq a)=P(z\geq \frac{a-\mu}{\sigma})$

We have a=9

$P(X\geq 9)=P(z\geq \frac{9-9.4}{4.2})=P(z\geq -0.1)$

$P(X\geq 9)=1-P(z$

$P(X\geq 9)=1-0.4602=0.5398\times 100=54$ %

Hence, the percentage of household throw out at least of paper a week=54%

7 0

3 years ago

When resistance is decreased in a circuit, current will _________.

Mars2501 [29]

The answer is A. Increase

The formula is <span>Voltage = Resistance X Current

Lets say the voltage is 10 and the resistence is 5

10 = 5 x current
Current = 2

Now, lets decrease the resistence from 5 to 2

10 = 2 x Current
Current = 5

The current increases
</span>

8 0

3 years ago

A snow ball is thrown upward at a speed of 27 m/s. How high is the snow ball 3.5 seconds later? Also, how fast is it moving at t

JulijaS [17]

Answer:

Dy = 111.66 [m]

t = 3.5 [s]

Explanation:

To solve this problem we must use the equations of kinematics.

$v_{f} = v_{o} - (g*t)\\$

where:

Vf = final velocity [m/s]

Vo = initial velocity = 27 [m/s]

g = gravity acceleration = 9.81 [m/s²]

t = time = 3.5 [s]

Note: The negative sign of the equation means that the gravity acceleration goes in opposite direction

Vf = 27 - (9,81*3,5)

Vf = - 7.33 [m/s] (this negative sign indicates that at this moment the snowball is going downwards)

To find how high the snowball was we must use the following equation:

$Dy=v_{o} *t+\frac{1}{2}*g*t$

Dy = (27*3.5) + (0.5*9.81*3.5)

Dy = 94.5 + (17.16)

Dy = 111.66 [m]

5 0

4 years ago

A rock is projected from the edge of the top of a building with an initial velocity of 12.2 m/s at an angle of 73° above the hor

Brrunno [24]

Answer:

7 s

Explanation:

u = Initial velocity of rock = 12.2 m/s

$\theta$ = Angle of throw = $73^{\circ}$

x = Displacement in x direction = 25 m

Displacement in x direction is given by

$x=u\cos\theta t\\\Rightarrow t=\dfrac{x}{u\cos\theta}\\\Rightarrow t=\dfrac{25}{12.2\times \cos73^{\circ}}\\\Rightarrow t=7\ \text{s}$

Time taken to reach the ground is 7 s.

4 0

3 years ago