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katen-ka-za [31]

2 years ago

11

A balloon is at a height of 81m and is ascending upwards with a velocity of 12m/s. A body of 2kg weight is dropped from it. If g

=10m/s2, the body will reach the surface of the earth in how much time?

1 answer:

kap26 [50]2 years ago

7 0

I know you are Indian by your question, HC Verma class 9 or 11 !!

if you got any problem, comment !!

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An object initially at rest experiences a constant horizontal acceleration due to the action of a resultant force applied for 10

Marianna [84]

Answer:

a = 18.28 ft/s²

Explanation:

given,

time of force application, t= 10 s

Work = 10 Btu

mass of the object = 15 lb

acceleration, a = ? ft/s²

1 btu = 778.15 ft.lbf

10 btu = 7781.5 ft.lbf

$m = \dfrac{15}{32.174}\ slug$

m = 0.466 slug

now,

work done is equal to change in kinetic energy

$W = \dfrac{1}{2} m (v_f^2-v_i^2)$

$7781.5 = \dfrac{1}{2}\times 0.466\times v_f^2$

$v_f = 182.75\ ft/s$

now, acceleration of object

$a = \dfrac{v_f-v_o}{t}$

$a = \dfrac{182.75-0}{10}$

a = 18.28 ft/s²

constant acceleration of the object is equal to 18.28 ft/s²

3 0

2 years ago

A crane uses a block and tackle to lift a 2200N flagstone to a height of 25m

Cloud [144]

Remember the headline: ENERGY IS NEVER CREATED OR DESTROYED

The amount of energy before and after are always equal. All we ever do with energy is move it around from one place to another.

a). A crane can't create energy. Lifting the same rock in 20 different ways always takes the <u><em>same amount of work</em></u>. It doesn't matter whether one person picks the rock straight up, or 50 people get around it and lift it, or roll it up a ramp, or lift it with 16 pulleys and a mile of rope, or use a giant steam crane.

You want to lift a 2200N weight up 25m, you're going to have to supply

(2200N) x (25m) = <em>55,000 Joules</em> of work.

c). YOU put out 55,000 Joules of energy. It had to GO someplace. Where is it now ? ===> It's the potential energy the rock has now, from being 25m higher than it was before. That <em>55,000 Joules</em> is NOW the potential energy of the rock.

No energy was created or destroyed. It just got moved around.

55,000 Joules of energy began as nuclear energy in the core of the sun. Solar radiation carried it to the Earth. Plants absorbed it, and stored it as chemical energy. You ... or a cow that you ate later ... ate the plants and took the chemical energy. One way or the other, the chemical energy got stored in your blood and fat. When you needed to put it out somewhere, you moved it into your muscles, and they converted it into mechanical energy. Then you used the mechanical energy to exert forces. Today, you used the original 55,000 joules to lift the flagstone, and NOW that energy is in the flagstone, 25 meters up off the ground !

6 0

2 years ago

1. A student is biking to school. She travels 0.7 km north, then realizes something has fallen out of her bag.

Snezhnost [94]

Explanation:

(a) Displacement of an object is the shortest path covered by it.

In this problem, a student is biking to school. She travels 0.7 km north, then realizes something has fallen out of her bag. She travels 0.3 km south to retrieve her item. She then travels 0.4 mi north to arrive at school.

0.4 miles = 0.64 km

displacement = 0.7-0.3+0.64 = 1.04 km

(b) Average velocity = total displacement/total time

t = 15 min = 0.25 hour

$v=\dfrac{1.04\ km}{0.25\ h}\\\\v=4.16\ km/h$

Hence, this is the required solution.

8 0

2 years ago

the minute hand on a clock is 9 cm long and travels through an arc of 252 degrees every 42 minutes. To the nearest tenth of a ce

Tanzania [10]

Answer:

The minutes hand travels 39.60 cm.

Explanation:

Note: a clock has a shape of a circle, the minutes hand is the radius, and the travel of the minutes hand forms a arc.

Length of an arc = ∅/360(2πr)

L = ∅/360(2πr).................... Equation 1π

Where L = length of an arc, ∅ = angle formed by an arc, r = radius of the arc.

Given: ∅ = 252°, r = 9 cm, π = 3.143.

Substituting these values into equation 1,

L = 252/360(2×3.143×9)

L = 0.7×2×3.143×9

L = 39.60 cm.

Thus the minutes hand travels 39.60 cm.

4 0

2 years ago

A car initially traveling at 24 m/s slams on the brakes and moves forward 196 m before coming to a complete halt. What was the m

Marrrta [24]

Answer:

$-1.47 m/s^2$

Explanation:

We can use the following SUVAT equation to solve the problem:

$v^2 - u^2 = 2ad$

where

v = 0 is the final velocity of the car

u = 24 m/s is the initial velocity

a is the acceleration

d = 196 m is the displacement of the car before coming to a stop

Solving the equation for a, we find the acceleration:

$a=\frac{v^2-u^2}{2d}=\frac{0-(24)^2}{2(196)}=-1.47 m/s^2$

4 0

2 years ago