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3 years ago

A ball is dropped from 215m. How long will it take to reach the ground? Use 9.8

Physics

1 answer:

valkas [14]3 years ago

7 0

Answer:

The time is $t = 6.62 \ s$

Explanation:

From the question we are told that

The height of the platform where the ball was dropped from is s = 215 m

The acceleration due to gravity is $g = 9.8 \ m/s^2$

Generally from kinematic equations

$s = ut + \frac{1}{2} gt^2$

Here u is the initial velocity of the ball and the value is u = 0 m/s given that the ball was at rest before it was dropped

$21 5 = 0 * t + \frac{1}{2} * 9.8t^2$

=> $21 5 = 4.9t^2$

=> $t^2 = \frac{215}{4.9}$

=> $t = 6.62 \ s$

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Assume that the Styrofoam slab and the fur are both initially neutral, and that the slab charged negatively after it is rubbed w

BARSIC [14]

Charging phenomenon is basically transfer of electrons from one system to other. When a system loses the electrons the it becomes positively charged and when a system gains electrons then it will become negatively charged

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Here it is given that slab get negatively charged so correct options are

<em>3. Electrons move from the fur to the slab. </em>

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3 years ago

Name the physical quantity measured by the velocity-time graph?

VARVARA [1.3K]

The so-called "velocity-time" graph is actually a "speed-time" graph. At any point
on it, the 'x'-coordinate is a time, and the 'y'-coordinate is the speed at that time.

'Velocity' is a speed AND a direction. Without a direction, you do not have a velocity,
and these graphs never show the direction of the motion. It seems to me that it would be
pretty tough to draw a graph that shows the direction of motion at every instant of time,
so my take is that you'll never see a true "velocity-time" graph.

At best, it would need a second line on it, whose 'y'-coordinate referred to a second
axis, calibrated in angle and representing the 'bearing' or 'heading' of the motion at
each instant. The graph of uniform circular motion, for example, would have a straight
horizontal line for speed, and a 'sawtooth' wave for direction.

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2 years ago

According to the law of conservation of energy, which statement must be true?

Nitella [24]

Answer:

B. A system cannot take in additional matter.

Explanation: The total amount of energy in the universe remains constant, it can merely change from one form to another.

Hope it helps you:)))

have a good day

5 0

1 year ago

Automobile A and B are initially 30 m apart travelling in adjacent highway lanes at speeds VA = 14.4 km/hr., VB 23.4 km/hr. at t

marshall27 [118]

Answer:

x = 240 m

Explanation:

This is a kinematics exercise

Let's fix our frame of reference on car A

x = x₀ₐ+ v₀ₐ t + ½ aₐ t²

the initial position of car a is zero

x = 0 + v₀ₐ t + ½ 0.8 t²

for car B

x = x_{ob} + v_{ob} t - ½ a_b t²

car B's starting position is 30 m

x = 30 + v_{ob} t - ½ 0.4 t²

at the point where they meet, the position of the two vehicles is the same

0 + v₀ₐ t + ½ 0.8 t² = 30 + v_{ob} t - ½ 0.4 t²

let's reduce the speeds to the SI system

v₀ₐ = 14.4 km / h (1000 m / 1 km) (1h / 3600s) = 4 m / s

v_{ob} = 23.4 km / h = 6.5 m / s

4 t + 0.4 t² = 30 + 6.5 t - 0.2 t²

0.2 t² - 2.5 t - 30 = 0

t² - 12.5 t - 150 = 0

we solve the quadratic equation

t = $\frac{12.5 \pm \sqrt{12.5^2 + 4 \ 150} }{2}$

t = $\frac{12.5 \ \pm 27.5}{2}$

t₁ = 20 s

t₂ = -7.5 s

time must be a positive quantity so the correct result is t = 20 s

let's look for the distance

x = 4 t + ½ 0.8 t²

x = 4 20 + ½ 0.8 20²

x = 240 m

8 0

2 years ago

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liraira [26]

Answer:

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Explanation:

5 0

3 years ago