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2 years ago

How much work is done in accelerating a 2000 kg car from rest to a speed of 30 m/s?

1 answer:

8 0

The work done is the same as the amount of energy increase. The formula for kinetic energy is 122
1
2
m
v
2
.

The initial KE of the car is 12(1000)×202=200,000
1
2
(
1000
)
×
20
2
=
200
,
000
joules.

The final KE of the car is 12(1000)×302=450,000
1
2
(
1000
)
×
30
2
=
450
,
000
joules.

The difference between these is the amount of work done: 450,000−200,000=250,000
450
,
000
−
200
,
000
=
250
,
000
joules.
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<h2>It will take 0.125 seconds to reach the net.</h2>

Explanation:

Initial speed, u = 34 ft/s = 10.36 m/s

Acceleration, a = -9.81 m/s²

Displacement, s = Final height - Initial height = 8 - 4 = 4 ft = 1.22 m

We have equation of motion, s = ut + 0.5 at²

Substituting

s = ut + 0.5 at²

1.22 = 10.36 x t + 0.5 x -9.81 x t²

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t = 1.99 s or t = 0.125 seconds

Minimum time is 0.125 seconds.

It will take 0.125 seconds to reach the net.

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3 years ago

Three light bulbs are connected to a battery in a series circuit. How will the bulbs behave if the circuit is closed?

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all three will glow A

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3 years ago

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As a physics instructor hurries to the bus stop, her bus passes her, stops ahead, and begins loading passengers. She runs at 6.0

Alika [10]

velocity of the physics instructor with respect to bus

$v = 6 m/s$

acceleration of the bus is given as

$a = 2 m/s^2$

acceleration of instructor with respect to bus is given as

$a = -2 m/s^2$

now the maximum distance that instructor will move with respect to bus is given as

$v_f^2 - v_i^2 = 2 a d$

$0 - 6^2 = 2(-2)(d)$

$-36 = - 4 d$

$d = 9 m$

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3 years ago

The 0.15kg baseball has a speed of v=30 m/s just before it is struck by the bat. It then travels along the trajectory shown befo

notka56 [123]

The magnitude of the average impulsive force imparted to the ball if it is in contact with the bat is 6000 N

The mass of the baseball, m = 0.15 kg

The speed at which it moves, v = 30 m/s

Time at which the baseball was in contact with the bat, t = 0.75 ms

t = 0.75/1000 s

t = 0.00075 s

The impulsive force is given by the formula:

$F=\frac{mv}{t}$

Substitute m = 0.15 kg, v = 30, and t = 0.00075s into the formula above:

$F=\frac{0.15 \times 30}{0.00075} \\\\F=6000N$

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2 years ago

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Tema [17]

The amount of blood that flows through the venae cavea of the adult is 3750 ml more than that of the child.

This is the volume of fluid flowing in a vessel per unit time.

First, we need to get the volume of blood flowing through the venae cavae of the adult and the child in 1 hour, then subtract the volume of blood for the child from that of the adult.

Using,

V = F'm................ Equation 1

Where:

V = Volume of the blood
F' = Flow rate
m = mass of blood.

For the Adult,

Given:

m = 70 kg
F = 75 ml/kg

Substitute these values into equation 1

V = 70(75)
V = 5250 ml.

For the child,

Given:

m = 20 kg
F = 75 ml/kg

Substitute these values into equation 1 also

V = 75(20)
V = 1500 ml.

The amount of blood that flows more through the adult than the child is

A = 5250-1500
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Hence, the amount of blood that flows through the venae cavea of the adult is 3750 ml more than that of the child.

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2 years ago