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Natali [406]
3 years ago
7

A projectile is shot horizontally at 23.4 m/s from the roof of a building 55.0 m tall. What is the time necessary for the projec

tile to reach the ground below?
Physics
1 answer:
baherus [9]3 years ago
5 0
The horizontal speed has no effect on the answer. 

It doesn't matter whether you flick a marble horizontally from the roof,
fire a high-power rifle horizontally from the roof, drive a school bus straight
off the roof, or drop a bowling ball from the roof with zero horizontal speed. 
Their vertical speed is completely determined by gravity, (and it happens to
be the same for all of them).

Handy dandy formula for the distance covered by anything that starts out
with zero speed and accelerates to the end:

            Distance = (1/2) (acceleration) x (time)²

If the beginning of the journey is on Earth, then the acceleration is
9.8 m/s² ... the acceleration of gravity on Earth.  We'll assume that
the 55-meter rooftop in the question is part of a building on Earth.

                       55 meters  =  (1/2) (9.8 m/s²) x (time)²           

Divide each side
by  4.9 m/s² :            55 m / 4.9 m/s²  =  (time)²

                                 (time)²  =  (55/4.9)  sec²

Square-root
each side:                time  =  √(55/4.9 sec²)

                                           =      3.35 sec  .
You might be interested in
The length of a simple pendulum is 0.66 m, the pendulum bob has a mass of 310 grams, and it is released at an angle of 12 degree
lina2011 [118]
A) the periodic time is given by the equation;
 T= 2π√(L/g)
For the frequency will be obtained by 1/T (Hz)
T = 2 × 3.14 √ (0.66/9.81)
   = 6.28 × √0.0673
    = 1.6289 Seconds
Frequency = 1/T = f = 1/1.6289
 thus; frequency = 0.614 Hz

b)  The vertical distance, the height is given by
 h= 0.66 cos 12
 h = 0.65 m
Vertical fall at the lowest point = 0.66 - 0.65 = 0.01 m
Applying conservation of energy
energy lost (MgΔh) = KE gained (1/2mv²)
 mgh = 1/2mv²
  v² = 2gΔh = 2×9.81 × 0.01 
                   = 0.1962
v = 0.443 m/s

c) total energy = KE + GPE = KE when GPE is equal to zero (at the lowest point possible)
Thus total energy is equal to;
E = 1/2mv²
   = 1/2 × 0.310 × 0.443²
   = 0.0304 J


4 0
3 years ago
An object starts at rest. Its acceleration over 30 seconds is shown in the graph below:
ddd [48]

Answer:

The instantaneous speed of the object after the first five seconds is 12.5 m/s.

(C) is correct option.

Explanation:

Given that,

An object starts at rest. Its acceleration over 30 seconds.

We need to calculate the instantaneous speed of the object after the first five seconds

We know that,

Area under the acceleration -time graph gives speed.

According to figure,

speed = area\ of\ tringle

speed=\dfrac{1}{2}\times b\times h

speed =\dfrac{1}{2}\times5\times5

speed-12.5\ m/s

Hence, The instantaneous speed of the object after the first five seconds is 12.5 m/s.

6 0
3 years ago
Many years ago, scientists believed that an atom was the smallest unit of matter. Eventually, evidence was discovered that indic
dybincka [34]
Advances in technology used to study and observe atoms lead to the discovery of electrons, protons, nuetrons, and the quarq
7 0
3 years ago
Velocity of a machine is always greater than mechanical advantage? why​
MrRa [10]

Answer:The mechanical advantage of a machine is always less than its velocity ratio.It is because mechanical advantage decreases due to the friction and weight of moving parts of the machine, but the velocity ratio remains constant.

Explanation: hope this helps

3 0
2 years ago
!!HELP HELP!!
borishaifa [10]

Answer:

7.5s

Explanation:

Given parameters:

Velocity  = 30m/s

Deceleration  = 4m/s²

Unknown:

Time it takes for the car to come to complete rest  = ?

Solution:

 To solve this problem, we use the kinematics expression below:

        v  = u + at

 Since this is a deceleration

         v  = u - at

v is the final velocity

u is the initial velocity

a is the acceleration

t is the time taken

         v - u  = -at

         0  - 30  = -4 x t

              -30  = -4t

               t  = 7.5s

6 0
2 years ago
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