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An elevator car, with a mass of 450 kg is suspended by a single cable. At time = 0s, the elevator car is raised upward. The tens

Alexeev081 [22]

Answer:

33.33 m/s

Explanation:

m = 450 kg. T = 5000 N, t = 3 seconds,

let the net acceleration is a.

T = m a

a = 5000 / 450 = 11.11 m/s^2

u = 0 , v = ?

Let v be the velocity after 3 seconds.

Use first equation of motion

v = u + a t

v = 0 + 11.11 x 3 = 33.33 m/s

5 0

3 years ago

A girl stand 5m away from a large plane mirror.How far must she walk ti be 2m away from her image?

KonstantinChe [14]

Answer:

3m

Explanation:

If a girl is 5m away from a mirror, she needs to walk a further 3m to be 2m away from her image.

5m-3m = 2m

4 0

1 year ago

Two wheels having the same radius and mass rotate at the same angular velocity. One wheel is made with spokes so nearly all the

Mazyrski [523]

Answer:

C. The wheel with spokes has about twice the KE.

Explanation:

Given that

Mass , radius and the angular speed for both the wheels are same.

radius = r

Mass = m

Angular speed = ω

The angular kinetic energy KE given as

$KE=\dfrac{1}{2}I\omega ^2$

I=Moment of inertia for wheels

Wheel made of spokes

I₁ = m r²

Wheel like a disk

I₂ = 0.5 m r²

Now by comparing kinetic energy

$\dfrac{KE_1}{KE_2}=\dfrac{I_1}{I_2}$

$\dfrac{KE_1}{KE_2}=\dfrac{mr^2}{0.5mr^2}$

$\dfrac{KE_1}{KE_2}=2$

KE₁= 2 KE₂

Therefore answer is C.

5 0

2 years ago

A racing car reaches a speed of 42 m/s. It then begins a uniform negative acceleration, using its parachute and braking system,

NARA [144]

As per the question the initial speed of the car [ u] is 42 m/s.

The car applied its brake and comes to rest after 5.5 second.

The final velocity [v] of the car will be zero.

From the equation of kinematics we know that

$v=u+at$ [ here a stands for acceleration]

$0=42 +5.5a$

$a =\frac{-42}{5.5} m/s^2$

$a= -7.64 m/s^2$

Here a is taken negative as it the car is decelerating uniformly.

We are asked to calculate the stopping distance .

From equation of kinematics we know that

$S=ut+\frac{1}{2} at^2$ [here S is the distance]

$= 42*5.5 +\frac{1}{2} [-7.64] [5.5]^2 m$

$=115.445 m$ [ans]

8 0

2 years ago

Gravity and magnetism are both

ella [17]

Answer:

Explanation:

Comment

You have to read this carefully enough that you don't mix up energy and forces.

Gravity is a force. If you don't believe me try jumping off a building. Which way are you going to go and why? Down because gravity attracts your mass.

So Magnetism must be a force as well. It acts in one direction, but not a specific one the way gravity acts). It also either attracts or repulses (pushes an object away)

Answer A

3 0

1 year ago

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