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3 years ago

A rock falls from a cliff and hits the ground at a velocity of 31m/s. How long did it take to fall?

Physics

2 answers:

Paladinen [302]3 years ago

4 0

Answer:

i dont know man

Explanation:

i dont know man

Alex3 years ago

4 0

Answer:

t = 3.2 s

Explanation:

time can be found from from speed and gravity

v = gt

t = v/g

t = 31 / 9.8

t = 3.163265...

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What is the pressure of a 300 lb. object on a 100 sq. in. area?

denis23 [38]

Answer:

D. 3 psi

Explanation:

Pressure is defined as force acting per unit area and is numerically expressed as:

$P= \frac {F}{A}$

where P represent pressure, F is force and A is area where the force acts. Substituting 300 lb for force and 100 sq.in for area then pressure,

$P=\frac {300 lb}{100 in^{2}}= 3 \ psi$

Therefore, from the choices given, option D, 3psi is the right choice.

3 0

3 years ago

Jack and Jill are on two different floors of their high rise office building and looking out of their respective windows. Jack s

Maru [420]

Answer:

a) speed when Jack sees the pot : 12.92 meters per second

b) height difference 163.115 meters

Explanation:

First to calculate te initial speed we use the acceleration formula:

a= v1-v0/t

Acceleration being gravity's acceleration (9.8 m/s^2)

v1 being the speed when Jill sees the pot

v0 when Jack sees it

and t the time between

Solving for v0 it would be

v1 - a*t = v0

replacing

$58 m/s - 9.8 m/s^2 *4.6 s = v0 = 12.92 m/s$

For the second question we use the position formula setting y0 and t0 as the position and time when jack sees the pot. (and setting the positive axis downward I.E. one meter below jack would be 1m not -1m)

The formula is

$y0 + v0*t + 1/2 g *t^2 = yt$

replacing

$0m + 12.92m/s* 4.6 s + 1/2 * 9.8 m/s^2 * (4.6 s)^2 = 163.115 m$

5 0

3 years ago

Two long, straight wires, one above the other, are separated by a distance 2a and are parallel to the x-axis. Let the be in the

ivolga24 [154]

Answer:

field B = µ₀c I / 2πr

The field in the xy plane due to the fact that the two wires are perpendicular to the plane Bx and By are everywhere 0 on the plane.

a) Midway between, the Bz components cancel, so <0, 0, 0> T

b) Bz = µ₀ x I / 2πa + µ₀ x I / 2π(3a) = (µ₀ x I / 2π)(1/a + 1/3a)

Bz = (µ₀ x I / 2πr)(3/3a + 1/3a) = (µ₀x I / 2πr)(4 / 3a) = 2µ₀ x I / 3πa

c) By symmetry, Bz = -2µ₀ x I / 3πa (that is, down into the plane)

8 0

3 years ago

You observe three carts moving to the right. cart a moves to the right at nearly constant speed. cart b moves to the right, grad

alisha [4.7K]

The cart with speed increasing to the right ... cart-b ...
has a net force to the right acting on it.

The others ...

... Cart-a has no net force at all acting on it, so its speed isn't changing.

... Cart-c has a net force toward the left acting on it, so its speed
toward the left is INcreasing. (That's the same thing as its speed
toward the right DEcreasing.

7 0

3 years ago

The speed of sound at sea level is normally about 340 m/s. A car honks itshorn as it drives toward an observer. The frequency of

Romashka [77]

Answer:

Explanation:

Let the velocity of car be v . We shall apply doppler's effect . Here the car is running towards the observer .

f = f₀ x( $\frac{V}{V-v}$ )

Here f is apparent frequency f₀ is true frequency , V is velocity of sound and v is velocity of source .

Putting the values

860 = 800 x 340 / (340 - v )

1.075 = 340 / (340 - v )

365.5 - 1.075 v = 340

25.5 = 1.075 v

v = 23.72 m /s

4 0

3 years ago