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3 years ago

From what height should you drop a ball if you want it to hit the ground in exactly 3 seconds?

Physics

1 answer:

Trava [24]3 years ago

5 0

Answer:

44.1 m

Explanation:

Given:

v₀ = 0 m/s

a = -9.8 m/s²

t = 3 s

Find: Δy

Δy = v₀ t + ½ at²

Δy = (0 m/s) (3 s) + ½ (-9.8 m/s²) (3 s)²

Δy = -44.1 m

The ball should be dropped from 44.1 meters.

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Sarah, whose mass is 40 kg, is on her way to school after a winter storm when she accidentally slips on a patch of ice whose coe

RideAnS [48]

Sarah's acceleration is $-0.49 m/s^2$

Explanation:

The force of kinetic friction acting on Sarah has a magnitude which is given by:

$F_f = \mu mg$

where

$\mu$ is the coefficient of kinetic friction

m is Sarah's mass

g is the acceleration of gravity

Moreover, according to Newton's second law of motion, we know that the net force on Sarah is equal to its mass times its acceleration:

$F=ma$

where a is the acceleration

Since the force of friction is the only force acting on Sarah, we can say that the net force is equal to the force of friction, therefore:

$F=-\mu mg = ma$

where the negative sign is due to the fact that the force of friction has a direction opposite to the motion of Sarah. Solving for a, we find

$a=-\mu g$

And substituting the following values:

$\mu = 0.05$ (coefficient of friction)

$g=9.81 m/s^2$ (acceleration of gravity)

we find:

$a=-(0.05)(9.81)=-0.49 m/s^2$

Learn more about acceleration and forces:

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4 0

3 years ago

Current can be made to flow in a stationary conductor by ............................

lara31 [8.8K]

Answer:

A is the answer. Im only 12 and i hope this explanation helps you.

Explanation:

Lenz's Law of Electromagnetic Induction. Faraday's Law tells us that inducing a voltage into a conductor can be done by either passing it through a magnetic field, or by moving the magnetic field past the conductor and that if this conductor is part of a closed circuit, an electric current will flow.

3 0

3 years ago

A block with a mass of 9.00 kg is pulled at a constant speed across a horizontal tabletop with a spring scale. The scale reads 6

snow_tiger [21]

Answer:0.69

Explanation:

Coefficient of kinetic friction=f/R=61.8/90=0.69

7 0

3 years ago

A projectile is fired from the ground at a velocity of 30.0 m/s, 35.0 º from the horizontal. What is the maximum height the proj

Norma-Jean [14]

Answer:

Vy = V sin theta = 30 * ,574 = 17.2 m/s

t1 = 17.2 / 9.8 = 1.76 sec to reach max height

Max height = 17.2 * 1.76 - 1/2 * 4.9 * 1.76^2 = 15.1 m

H = V t - 1/2 g t^2 = 1.2 * 9.8 * 1.76^2 = 15.1 m

Time to fall from zero speed to ground = rise time = 1.76 sec

Vx = V cos 35 = 24.6 m / sec horizontal speed

Time in air = 1.76 * 2 = 3.52 sec before returning to ground

S = 24.6 * 3.52 = 86.6 m

8 0

2 years ago

Potential difference of a battery is 2.2 V when it is connected

Alchen [17]

Answer:

1.1ohms

Explanation:

According to ohms law E = IR

If potential difference of a battery is 2.2 V when it is connected across a resistance of 5 ohm and if suddenly the voltage Falls to 1.8V then the current in the 5ohms resistor I = V/R = 1.8/5

I = 0.36A (This will be the load current).

Before we can calculate the value of the internal resistance, we need to know the voltage drop across the internal resistance.

Voltage drop = 2.2V - 1.8V = 0.4V

Then we calculate the internal resistance using ohms law.

According to the law, V = Ir

V= voltage drop

I is the load current

r = internal resistance

0.4 = 0.36r

r = 0.4/0.36

r = 1.1 ohms

6 0

3 years ago