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vlada-n [284]
2 years ago
15

Demarcus launches a small weight into the air. The weight takes 6.4 seconds to reach the ground again. At what time did the weig

ht have a vertical velocity of 0 meters per second?

Physics
1 answer:
Monica [59]2 years ago
5 0
The answer is A.
During the process, the only force imposed on the small weight is gravity.
The time from launching to the highest is the same as the time from the highest to the ground. And the vertical velocity at 0 m/s is at the highest position.
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A flow is isentropically expanded to supersonic speeds in a convergent-divergent nozzle. The reservoir and exit pressures are 1.
Kamila [148]

Answer:

Ae/A* = 1.115

Explanation:

Let the reservoir pressure be  p_0

Let the exit  pressure be p_e

Ratio of reservoir pressure and exit pressure

\frac{p_o}{p_e} = \frac{1}{0.3143}

  = 3.182

For the above value of pressure ratio

Obtain the area ratio from the isentropic flow table

Ae/A* = 1.115

The value of pressure ratio is Ae/A* = 1.115

6 0
3 years ago
PLEASE ANSWER FAST In which of the following situations is the greatest amount of work accomplished? 1. A boy lifts a 2-newton b
GuDViN [60]

Explanation:

Work done is given by the product of force and displacement.

Case 1,

1. A boy lifts a 2-newton box 0.8 meters.

W = 2 N × 0.8 m = 1.6 J

2. A boy lifts a 5-newton box 0.8 meters.

W = 5 N × 0.8 m = 4 J

3. A boy lifts a 8-newton box 0.2 meters.

W = 8 N × 0.2 m = 1.6 J

4. A boy lifts a 10-newton box 0.2 meters.

W = 10 N × 0.2 m = 2 J

Out of the four options, in option (2) ''A boy lifts a 5-newton box 0.8 meters'', the work done is 4 J. Hence, the greatest work done is 4 J.

3 0
3 years ago
When Jane drives to work, she always places her purse on the passenger’s seat. By the time she gets to work, her purse has falle
madam [21]

Answer:

the vibrations push the purse up and down very fast and gravity pushes the purse down onto the floor

Explanation: does that help

7 0
3 years ago
Four objects are situated along the y axis as follows: a 1.93-kg object is at +2.91 m, a 2.95-kg object is at +2.43 m, a 2.41-kg
Anna [14]

Answer:

0.958 m

Explanation:

So the total mass of the system is

M = 1.93 + 2.95 + 2.41 + 3.99 = 11.28  kg

let y be the distance from the center of mass to the origin. With the reference to the origin then we have the following equation

My = m_1y_1 + m_2y_2 +m_3y_3 + m_4y_4

11.28y = 1.93*2.91 + 2.95*2.43 + 2.41*0 + 3.99*(-0.496) = 10.806

y = \frac{10.806}{11.28} = 0.958 m

So the center of mass is 0.958 m from the origin

3 0
3 years ago
If he were able to maintain this constant rate of acceleration, what would have been his speed as he finished the race?
Law Incorporation [45]

a) 4.8 m/s² his average acceleration during the first 2.5 s

b) 15 m distance he cover during the first 2.5 seconds.

c) 31 m/s his speed as he finished the race.

<h3>(a) How to calculate the Average Acceleration ?</h3>

Average acceleration is calculated by using Newtons first law of motion

v = u + at

where

u is initial velocity

v is final velocity

a is constant acceleration

t is time

Given u = 0m/s , v = 12 m/s and t = 2.5 sec

Therefore average acceleration is given by

a=\frac{v}{t}

a=\frac{12}{2.5}

a = 4.8 m/sec²

b) Here we will use newtons second law of motion

s=ut+\frac{1}{2}at^{2}

On substituting value we get

s = 15m

c) Here we will use newtons third law of motion

v² = u² + 2as

Here u = 0 , a = 4.8 m/s² and s = 100 m

Therefore

v² = 960

v = 31 m/s

Disclaimer: the question was given incomplete in the portal. Here is the complete question.

Question: Usain Bolt's 100m sprint Runner set the world record for the100 meter sprint during the 2009World Championships in Berlin with a time of 9.58 s, reaching a top speed of 12 m/s in about 2.5 s.

a. What was his average acceleration during the first 2.5 s?

b. What distance did he cover during the first 2.5 seconds, assuming his acceleration was constant?

c. If he were able to maintain this constant rate of acceleration, what would have been his speed as he finished the race?

Learn more about Newtons law of motion here:

brainly.com/question/12525794

#SPJ4

5 0
2 years ago
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