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3 years ago

1. Which Law? When you are standing up in a subway train, and the train suddenly stops, your body continues to go forward.

Physics

1 answer:

riadik2000 [5.3K]3 years ago

6 0

1. Law 1, since there is no other force acting on your body as you stand there, so you will continue to go forward.

2. Law 3, since the swimmer is using opposite forces to propel herself through the water. She generates a force by pushing the water which helps to push her forward.

3. Law 2, since you are giving the motorcycle more energy as a result of the gas being transformed into the energy that helps to accelerate the motorcycle's speed.

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If a car goes at a speed of 80 kph in 10 seconds, what is the distance

Blababa [14]

Answer:222 meters

Explanation:

Speed=80kph=(80x5/18)=(80x5)/18=22.2m/s

Time=10 seconds

distance=speed x time

distance=22.2 x 10

distance=222

distance=222 meters

3 0

4 years ago

How much heat energy in megajoules is needed to convert 7 kilograms of ice at -9c to water at 0c

Musya8 [376]

The latent heat of fusion of water is 344 j/p.This will take 344x300 or 100200 J to melt the ice. once it melted its at oc

6 0

4 years ago

Read 2 more answers

An empty 2,500 kg train car is headed northbound at a velocity of 5 m/s. Ahead of the first car, an empty 1,500 kg car is headed

Tema [17]

Let the mass of 2500 kg car be $m_1$ and it's velocity be $v_1$ and the mass of 1500 kg car be $m_2$ and it's velocity be $v_2$ .

After the bumping the mass be M and it's velocity be V.

By law of conservation of momentum we have

$m_1v_1+m_2v_2 = MV$

2500 * 5 + 1500 * 1=4000 * V

V = 14000/4000 = 7/2 = 3.5 m/s

So the velocity of the two-car train = 3.5 m/s

9 0

3 years ago

A 300 g glass thermometer initially at 23 ◦C is put into 236 cm3 of hot water at 87 ◦C. Find the final temperature of the thermo

DIA [1.3K]

Answer:

$74^{\circ} C$

Explanation:

We are given that

Mass of glass, $m=300 g$

$T_1=23^{\circ}$

Volume, $V=236cm^3$

Mass of water= $density\times volume=1\times 236=236 g$

Density of water= $1g/cm^3$

Temperature of hot water, $T=87^{\circ}$

Specific heat of glass, $C_g=0.2cal/g^{\circ}C$

Specific heat of water, $C_w=1 cal/g^{\circ}C$

$Q_{glass}=m_gC_g(T_f-T_1)=300\times 0.2(T_f-23)$

$Q_{water}=m_wC_w(T_f-T)=236\times 1(T_f-87)$

$Q_{glass}+Q_{water}=0$

$300\times 0.2(T_f-23)+236\times 1(T_f-87)$

$60T_f-1380+236T_f-20532=0$

$296T_f=20532+1380=21912$

$T_f=\frac{21912}{296}=74^{\circ} C$

5 0

3 years ago

Question 2 (10 points)

kenny6666 [7]

The force required to slow the truck was -5020 N

Explanation:

First of all, we find the acceleration of the truck, which is given by

$a=\frac{v-u}{t}$

where

v is the final velocity

u is the initial velocity

t is the time

For the truck in this problem,

v = 11.5 m/s

u = 21.9 m/s

t = 2.88 s

So the acceleration is

$a=\frac{11.5-21.9}{2.88}=-3.6 m/s^2$

where the negative sign means that this is a deceleration.

Now we can find the force exerted on the truck, which is given by Newton's second law:

$F=ma$

where

m = 1390 kg is the mass of the truck

$a=-3.6 m/s^2$ is the acceleration

And substituting,

$F=(1390)(-3.6)=-5004 N$

So the closest answer among the option is -5020 N.

Learn more about acceleration and forces:

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#LearnwithBrainly

8 0

3 years ago