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3 years ago

3. A bird flying 4 m/s has 8 joules of kinetic energy. What is the mass of the bird?

Physics

1 answer:

lesya692 [45]3 years ago

3 0

Answer:

The mass of the bird is 1 [kg]

Explanation:

The kinetic energy is defined by the following equation:

$E_{k} =\frac{1}{2} *m*v^{2}\\$

where:

m= mass of the bird [kg]

v = velocity of the bird [m/s]

Ek = kinetic energy [J]

We need to clear the mass from the equation given.

$m=\frac{2*E_{k} }{v^{2}} \\m=\frac{2*8}{(4)^{2} } \\m=1 [kg]$

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Streak is a reliable identifier of a mineral. true or false

inysia [295]

Answer:

true?

Explanation:

Im positive but not 100% sure wait for someone else to answer and see if they say the same.

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3 years ago

Read 2 more answers

The momentum of a 0.1 kg object traveling at 2000 m/s is 20,000 kg·m/s. True or False

Alina [70]

That's false.

The definition of momentum is (mass) x (speed), so they must be multiplied.

"20,000 kg-m/s" has the correct units resulting from multiplication, but the number could only be the result of division.

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3 years ago

You and a highway patrolman are driving at constant speeds in opposite directions on a straight highway. The patrolman is drivin

kompoz [17]

Answer: 75 mph

Explanation:

The Relative Speed for a mobile is equal to the diference between the object and the observer:

Relative Speed (Rs) = Object's Velocity - Observer's Velocity

Thinking on those terms, we would need to have a universal observer to do any understandable measurement on daily basics. This is why we all use earth as a Static Observer for every measurement we do everyday.

Using Earth as an observer, the Velocity for the Patrolman is:

Patrolman Velocity (Vp) = 60 mph

Because the radar gun does measure the Relative Speed for the object, which is 135 mph, we need to work with the equation to find the Velocity using Earth as a reference.

Object's Relative Velocity = Object's Velocity - Patrolman's Velocity

Object's Velocity = Object's Relative Velocity + Patrolman's Velocity

We need to keep in mind, the Patrolman is going on the opposite direction. Because of this the sign for his velocity should be negative.

Object's Velocity = 135 mph + ( -60 mph)

Object's Velocity = 135 mph - 60 mph

Object's Velocity = 75 mph

3 0

3 years ago

A 2000-kg railway freight car coasts at 4.4 m/s underneath a grain terminal, which dumps grain directly down into the freight ca

ruslelena [56]

Answer:

933. 3kg

Explanation:

We are given that

Mass,m=2000 kg

Initial speed,u=4.4 m/s

We have to find the maximum mass of grain if the speed of loaded freight car must not go below 3.0 m/s.

Final speed,v=3 m/s

By conservation of momentum

Initial momentum=Final momentum

$mu=m'v$

Substitute the values

$2000\times 4.4=m'(3)$

$m'=\frac{2000\times 4.4}{3}$

$m'=2.93\times 10^3 kg$

Mass of freight loaded car=2933.3 kg

Mass of grains=2933.3-2000=933.3 kg

Hence, the maximum mass of grains that it can accept=933.3 kg

7 0

3 years ago

A crane carries a 1600 kg car at 1.5 m/s^2 with a chain that has a negligible mass. If the coefficient of kinetic friction betwe

padilas [110]

Answer:

option (d) 7.1 kN

Explanation:

Given:

Mass of the car, m = 1600 kg

Acceleration of the car, a = 1.5 m/s²

Coefficient of kinetic friction = 0.3

let the tension be 'T'

Now,

ma = T - f .................(1)

where f is the frictional force

also,

f = 0.3 × mg

where g is the acceleration due to the gravity

thus,

f = 0.3 × 1600 × 9.81 =

therefore,

equation 1 becomes

1600 × 1.5 = T - 4708.8

T = 2400 + 4708.8

T = 7108.8 N

T = 7.108 kN

Hence,

The correct answer is option (d) 7.1 kN

6 0

3 years ago