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3 years ago

13

When a driver hits the brakes, his car decelerates from 50m/s at a uniform rate of 2.0m/s^2. His car stops after covering some d

istance. How long does it take him to stop?

1 answer:

Assoli18 [71]3 years ago

7 0

Please find attached photograph for your answer. Please do comment whether it is useful or not.

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What is the impulse of a 3 kg object that starts from rest and moves to 20 m/s?

IrinaK [193]

Answer:

The impulse on the object is 60Ns.

Explanation:

Impulse is defined as the product of the force applied on an object and the time at which it acts. It is also the change in the momentum of a body.

F = m a

F = m( $\frac{v_{2} - v_{1} }{t}$ )

⇒ Ft = m( $v_{2}$ - $v_{1}$ )

where: F is the dorce on the object, t is the time at which it acts, m is the mass of the object, $v_{1}$ is its initialvelocity and $v_{2}$ is the final velocity of the object.

Therefore,

impulse = Ft = m( $v_{2}$ - $v_{1}$ )

From the question, m = 3kg, $v_{1}$ = 0m/s and $v_{2}$ = 20m/s.

So that,

Impulse = 3 (20 - 0)

= 3(20)

= 60Ns

The impulse on the object is 60Ns.

8 0

3 years ago

An experimental tungsten light bulb filament has a length of 5 cm and a diameter of 0.074 cm. The filament is basically just a w

adell [148]

Answer:

power emitted is 1.75 W

Explanation:

given data

length l = 5 cm = 5 × $10^{-2}$ m

diameter d = 0.074 cm = 74 × $10^{-5}$ m

total filament emissivity = 0.300

temperature = 3068 K

to find out

power emitted

solution

we find first area that is π×d×L

area = π×d×L

area = π×74 × $10^{-5}$ ×5 × $10^{-2}$

area = 1162.3892 × $10^{-5}$ m²

so here power emitted is express as

power emitted = E × σ × area × (temperature)^4

put here all value

power emitted = 0.300× 5.67 × 1162.3892 × $10^{-5}$ × (3068)^4

power emitted = 1.75 W

5 0

3 years ago

A cello string 0.75 m long has a 220 hz fundamental frequency. find the wave speed along the vibrating string. answer in units o

maxonik [38]

For fundamental frequency of a string to occur, the length of the string has to be half the wavelength. That is,

1/2y = L, where L = length of the string, y = wavelength.

Therefore,
y = 2L = 2*0.75 =1.5 m

Additionally,
y = v/f Where v = wave speed, and f = ferquncy

Then,
v = y*f = 1.5*220 = 330 m/s

4 0

3 years ago

Calculat the acceleration of a person at latitude<br> 40degreesowing to the rotation of the earth.

beks73 [17]

Answer:

acceleration of person = 9.77 m/s²

Explanation:

given data

latitude = 40 degree

to find out

Calculate the acceleration of a person

solution

we know that here 40 degree = 0.698 rad

so

acceleration of person = g - ω²R ...............1

and 1 rotation complete in 24 hours = 360 degree

here g is 9.81

so we know Earth angular speed ω = 7.27 × $10^{-5}$ rad/s and R is earth radius that is 6.37 × $10^{6}$ m

so

put here value in equation 1 we get

acceleration of person = g - ω²R

acceleration of person = 9.81 - (7.27 × $10^{-5}$ )² × 6.37 × $10^{6}$

acceleration of person = 9.77 m/s²

6 0

4 years ago

You push on a cart (18.0kg) at a 30 degree below horizontal angle. The coefficient of kinetic friction between the chair and the

podryga [215]

Given that force is applied at an angle of 30 degree below the horizontal

So let say force applied if F

now its two components are given as

$F_x = Fcos30$

$F_y = Fsin30$

Now the normal force on the block is given as

$N = Fsin30 + mg$

$N = 0.5F + (18\times 9.8)$

$N = 0.5F + 176.4$

now the friction force on the cart is given as

$F_f = \mu N$

$F_f = 0.625(0.5F + 176.4)$

$F_f = 110.25 + 0.3125F$

now if cart moves with constant speed then net force on cart must be zero

so now we have

$F_f + F_x = 0$

$Fcos30 - (110.25 + 0.3125F) = 0$

$0.866F - 0.3125F = 110.25$

$F = 199.2 N$

so the force must be 199.2 N

8 0

3 years ago