Divers in Acapulco dive from a cliff that is 65 m high. If the rocks below the cliff extend outward for 25 m, how fast must the diver be
going when he jumps if he just barely clears the rocks? Provide evidence.

Cool question! First step is to find the time taken to fall

57

m

, then to find the horizontal velocity needed to cover

24

m

in that time. In this case the answer is

7.0

m

s

−

1

.

Explanation:

This is a less typical projectile motion question, but it's still projectile motion. This means the horizontal and vertical directions can be considered separately. We assume that the initial vertical velocity,

u

y

=

0

m

s

−

1

, and we are trying to find the required initial horizontal velocity,

u

x

.

To find the time taken to fall

57

m

:

s

=

u

t

+

1

2

a

t

2

Since

u

=

0

, we can rearrange this to:

t

=

√

2

s

a

=

√

2

⋅

57

9.8

=

3.41

s

The horizontal velocity will be constant (ignoring air resistance), so to cover

24

m

in

3.41

s

will be given by:

v

=

s

t

→

u

x

=

24

3.41

=

7.0

m

s

−

1

Answer link

most voltage drop calculators want the distance between the source and destination. then internally, they double it so both the source and return wires are calculated. but you need to know which distance the calculator uses so you're not half of what you should be or double what you should be.

most circuit breakers will not take a #6 directly, so the electrician will have to splice on a smaller pigtail. you also have to upsize the grounding wire when you upsized the ungrounded (hot) wire (see note in 250.122). this will preclude using most cable assemblies, as a cable with #6 copper will most likely only have a #10 grounding conductor. you need a #6 grounding conductor if the circuit is 20a. a #8 cable is no better, as it will have a #10 grounding conductor too. but most 20a breakers will take a #8 directly.

in your related post, you didn't say what type of load this is. if it is a light or heater, voltage drop won't be a big issue. if this is a motor, the current needs are huge at startup and the voltage drop can pose a problem. if this is a motor, knowing if the motor is under much load during startup will answer the voltage drop effect (a saw is easier to start than a compressor).

speed

ratio of distance traveled to time interval

net force

vector sum of forces on object

object

source of diverging light rays either luminous or illuminated

don't remove my answer im trying my best to answer them

explanation: