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3 years ago

8

What is a controlled experiment? none of the variables are changed all variables are kept constant two variables are changed at

a time one variable is changed at a time

1 answer:

Ostrovityanka [42]3 years ago

7 0

One variable is changed at a time

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A heavy hall with a mass of 3.5 kg is observed to accelerate

LenKa [72]

Answer:

<h2>21 N</h2>

Explanation:

The force acting on an object given it's mass and acceleration can be found by using the formula

force = mass × acceleration

From the question we have

force = 3.5 × 6

We have the final answer as

<h3>21 N</h3>

Hope this helps you

6 0

3 years ago

How many cubic feet are in a 55-gallon drum?

san4es73 [151]

1 gallon = 231 cubic inches
1 cubic foot = 1728 cubic inches

   (55 gal) x (231 in³/gal) x (1 ft³/1728 in³)

   = (55 x 231 / 1728) ft³

   = 7.352 cubic feet (rounded)

5 0

3 years ago

LOTS OF POINTSA rocket of mass 40 000 kg takes off and flies to a height of 2.5 km as its engines produce 500 000 N of thrust.

Svetradugi [14.3K]

Answer:

i) E = 269 [MJ] ii)v = 116 [m/s]

Explanation:

This is a problem that encompasses the work and principle of energy conservation.

In this way, we establish the equation for the principle of conservation and energy.

i)

$E_{k1}+W_{1-2}=E_{k2}\\where:\\E_{k1}= kinetic energy at moment 1\\W_{1-2}= work between moments 1 and 2.\\E_{k2}= kinetic energy at moment 2.$

$W_{1-2}= (F*d) - (m*g*h)\\W_{1-2}=(500000*2.5*10^3)-(40000*9.81*2.5*10^3)\\W_{1-2}= 269*10^6[J] or 269 [MJ]$

At that point the speed 1 is equal to zero, since the maximum height achieved was 2.5 [km]. So this calculated work corresponds to the energy of the rocket.

Er = 269*10^6[J]

ii ) With the energy calculated at the previous point, we can calculate the speed developed.

$E_{k2}=0.5*m*v^2\\269*10^6=0.5*40000*v^2\\v=\sqrt{\frac{269*10^6}{0.5*40000} }\\ v=116[m/s]$

8 0

2 years ago

A disc is thrown through the air for 1.5 min with a power output of 12.5 W. How much work is done when throwing the disc?

klasskru [66]

Answer:

work = 1125 [J]

Explanation:

To solve this problem we must remember the definition of power, which is defined as the relationship between work and time. The power can be calculated using the following equation:

Power = work/time

Power = 12.5 [w]

work = joules [J]

time = 1.5 [min] = 90 [s]

work = 12.5*90

work = 1125 [J]

7 0

3 years ago

A boat moves up and down as water waves pass under the boat. If the amplitude of the wave gets bigger, then

xeze [42]

The anwser is A or D

7 0

2 years ago

Read 2 more answers