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Mrac [35]
3 years ago
11

As a science project, you drop a watermelon off the top of the Empire State Building, 320 m above the sidewalk. It so happens th

at Superman flies by at the instant you release the watermelon. Superman is headed straight down with a speed of 39.0 m/s.
How fast is the watermelon going when it passes Superman?
Physics
1 answer:
SSSSS [86.1K]3 years ago
3 0

Answer:

The velocity of watermelon when it passes Superman is 78 m/s.

Explanation:

Height of the building, d = 320 m

Speed of the superman, v = 39 m/s

We need to find the speed of watermelon when it passes Superman. Let t is the time taken by the watermelon. So,

d=ut+\dfrac{1}{2}gt^2

Here u = 0

d=\dfrac{1}{2}gt^2

39t=\dfrac{1}{2}\times 9.8\times t^2

t = 7.95 seconds

Let v is the speed of the watermelon. It is given by :

v=gt

v=9.8\times 7.95

v = 77.91 m/s

or

v = 78 m/s

So, the velocity of watermelon when it passes Superman is 78 m/s.

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a body initially at rest, starts moving with a constant acceleration of 2ms-2 .calculate the velocity acquired and the distance
Marta_Voda [28]

a) 10 m/s

b) 25 m

Explanation:

a)

The body is moving with a constant acceleration, therefore we can solve the problem by using the following suvat equation:

v=u+at

where

u is the initial velocity

v is the final velocity

a is the acceleration

t is the time

For the body in this problem:

u = 0 (the body starts from rest)

a=2 m/s^2 is the acceleration

t = 5 s is the time

So, the final velocity is

v=0+(2)(5)=10 m/s

b)

In this second part, we want to calculate the distance travelled by the body.

We can do it by using another suvat equation:

v^2-u^2=2as

where

u is the initial velocity

v is the final velocity

a is the acceleration

s is the distance travelled

Here we have

u = 0 (the body starts from rest)

a=2 m/s^2 is the acceleration

v = 10 m/s is the final velocity

Solving for s,

s=\frac{10^2-0^2}{2(2)}=25 m

3 0
3 years ago
2. Connect concepts on the left with a description on the right.
Nuetrik [128]

plzzz explain me your questions

8 0
2 years ago
Which best explains why a wood-burning fireplace does not represent a closed system? A. because a fire requires oxygen from the
sweet [91]
Answer is A of course lol Fire needs oxygen as an essential fuel to burn.
7 0
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On a safety test course, a 1000 kg car heading north at 5 m/s collides head-on with an 800 kg car heading south at 4 m/s. At the
Luden [163]

Answer:

The speed is 3.5\frac{m}{s} and the direction is heading north.

Explanation:

In collisions the force exerted by the objects that collide is higher enough than the external forces that we can neglect that external forces, with that assumption we can use the conservation fo momentum law that states, final total momentum (pf) is equal initial total momentum (pi) if there’re not external forces or they are small enough to be neglected. Mathematically:

p_f=p_i

The total momentum is the sum of the momentum of each of the bodies we're dealing, in our case the moment of each car, then:

p_{nf}+p_{sf}=p_{ni}+p_{si}

with pn the momentum of the 1000kg car heading north and ps the 800kg car heading south. Momentum is defined as mass times velocity, then:

m_nv_{nf}+m_sv_{sf}=m_nv_{ni}+m_sv_{si} (1)

It's important to note that when we talk about momentum and velocity direction matters, so we're are going to choose a system of reference where quantities pointing north are positive and pointing south are negative. So, the initial velocity of 1000 kg car is vni=5 m/s, initial velocity of 800 kg car is vsi=-4 m/s and the final velocity of 1000 kg car is vnf=-1 m/s. Now we can solve (1) for vsf and use the values we already have:

v_{sf}=\frac{m_nv_{ni}+m_sv_{si}-m_nv_{nf}}{m_s}=\frac{(1000)(5)+(800)(-4)-(1000)(-1)}{800}

v_{sf}=3.5\frac{m}{s}

Because the sign is positive the direction is to heading north.

7 0
3 years ago
During an earthquake you should.
White raven [17]

Well, you should TAKE COVER UNDER A STUDY DESK, TABLE OR AGAINST AN INSIDE WALL. Which is C. This is because, doing this protects you from the falling objects. If you do A or B, you will probably get crushed by falling objects because you are exposed. Hope I helped.
3 0
3 years ago
Read 2 more answers
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