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3 years ago

PE=30J, m=?, g=10m/s2, h=10m

1 answer:

5 0

Based on the given, this is probably a gravitational potential energy problem (PEgrav). The formula for PEgrav is:

PEgrav = mgh

Where:
m = mass (kg)
g = acceleration due to gravity
h = height (m)

With this formula you can derive the formula for your unknown, which is mass. First put in what you know and then solve for what you do not know.

$PEgrav=mgh$
$30J=m(10)(10[tex] \frac{30}{100} =m$ )[/tex]

Do operations that you can with what is given first.

$30J=m(100m)$

Transpose the 100 to the other side of the equation. Do not forget that when you transpose, you do the opposite operation.

$\frac{30}{100} =m$

m = 0.30kg

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3 years ago

John see Hua running towards him at 11m/s. While running, Hua throws a ball to john at 5m/s. What is the speed of the ball as ob

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3 years ago

Consider a car travelling at 60 km/hr. If the radius of a tire is 25 cm, calculate the angular speed of a point on the outer edg

KengaRu [80]

Answer

given,

speed of car = 60 km/hr

= 60 x 0.278 m/s

= 16.68 m/s

radius of the tire = 25 cm = 0.25 m

time taken to stop = 6 s

average acceleration = ?

$\omega = \dfrac{v}{R}$

$\omega = \dfrac{16.68}{0.25}$

$\omega =66.72 rad/s$

average acceleration= $\dfrac{\Delta \omega}{\Delta t}$

= $\dfrac{66.72}{6}$

= 11.12 rad/s²

correct answer option D

b) length of sea saw = 10 m

mass of jack = 100 Kg

mass of Jill = 60 Kg

Let y be the distance from the Jack. To balance the seesaw moment on both side should balance each other about fulcrum

now,

100 x y = 5 x 60

y = 3 m

the correct answer is option B

4 0

3 years ago

A plane is flying horizontally with speed

Kay [80]

Answer:

2. ahead of the package.

Explanation:

Using y' - y = ut - 1/2gt², we find the time, t it takes the package to hit the ground. So, u = initial vertical velocity of package = 0 m/s, y = initial position of package = 3970 m, y' = final position of package = 0 m, g = acceleration due to gravity = 9.8 m/s².

Substituting the variables into the equation, we have

y' - y = ut - 1/2gt²

0 m - 3970 m = 0t - 1/2 × (9.8 m/s²)t²

-3970 m = -(4.9m/s²)t²

t² = -3970 m ÷ -4.9 m/s²

t² = 810.2 s²

t = √810.2 s²

t = 28.5 s

Using v = u' + at, we find the horizontal acceleration of the plane. Since the initial horizontal velocity of the package is that of the plane, u' = 162 m/s, v = 0 m/s since the package stops and t = 28.5 s when the package stops.

So, a = (v - u')/t

a = (0 m/s - 162 m/s)/28.5 s

a = -162 m/s/28.5 s

a = -5.68 m/s²

Using v² = u'² + 2as, we find the horizontal distance ,s where the package stops.

So, s = (v² - u'²)/2a

Substituting the values of the variables, we have

s = ((0 m/s)² - (162 m/s)²)/(2 × -5.68 m/s²)

= - 162 m²/s²/(-11.36 m/s²)

= 14.26 m

The horizontal distance d the plane moves after releasing the package is d = u't = 162 m/s × 28.5 s = 4617 m

Since d = 4617 m > s = 14.26 m, the plane would be ahead of the package when the package hits the ground.

6 0

3 years ago

A boy takes 20 minutes to cover 3.2 km on a bicycle find the speed in km/hr

Murrr4er [49]

Answer:

9.6 km/h

Explanation:

20 minutes=1/3 minute.

The speed of the bicycle: 3.2:1/3=9.6 km/h.

Answer: 9.6 km/h

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3 years ago