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2 years ago

A 2,000-kilogram car uses a braking force of 12,000 Newton to stop in 5 seconds. What is its initial speed of the car?

2 answers:

5 0

First, solve for the acceleration of the car. You know the mass of the car and the braking force, so you can use the equation Force = Mass x Acceleration. This gives you 12,000 = 2,000 x A. Divide 12,000 by 2,000 to find the acceleration equal to 6 m/s^2. This is the rate that the car is slowing down at. Velocity is equal to accleration x time (rate x time), so you multiply 6 by the time of 5 seconds. This leaves you with a velocity of 30 m/s or about 67.1 mph.

jeka942 years ago

3 0

<u>Answer:</u> The initial speed of the car is 30 m/s

<u>Explanation:</u>

Force is defined as the push or pull on an object with some mass that causes change in its velocity.

It is also defined as the mass multiplied by the acceleration of the object.

Mathematically,

$F=m\times a$

where,

F = force exerted on the car = 12,000 N

m = mass of the car = 2,000 kg

a = acceleration of the car = ?

Putting values in above equation, we get:

$12000kg.m/s^2=2000kg\times a\\\\a=\frac{12000}{2000}=6m/s^2$

To calculate the initial speed of the car, we use first equation of motion:

$v=u+at$

where,

v = final speed of the car = 0 m/s (brakes are applied)

u = initial speed of the car = ?

a = acceleration of the car = $-6m/s^2$ (as the car is getting stopped)

t = time taken = 5 sec

Putting values in above equation, we get:

$0=u+(-6\times 5)\\\\u=0+30\\\\u=30m/s$

Hence, the initial speed of the car is 30 m/s

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A uniform magnetic field is perpendicular to the plane of a circular loop of diameter 13 cm formed from wire of diameter 2.6 mm

I am Lyosha [343]

Answer:

Rate of change of magnetic field is $3.466\times 10^3T/sec$

Explanation:

We have given diameter of the circular loop is 13 cm = 0.13 m

So radius of the circular loop $r=\frac{0.13}{2}=0.065m$

Length of the circular loop $L=2\pi r=2\times 3.14\times 0.065=0.4082m$

Wire is made up of diameter of 2.6 mm

So radius $r=\frac{2.6}{2}=1.3mm=0.0013m$

Cross sectional area of wire $A=\pi r^2=3.14\times0.0013^2=5.30\times 10^{-6}m^2$

Resistivity of wire $\rho =2.18\times 10^{-8}m$

Resistance of wire $R=\frac{\rho L}{A}=\frac{2.18\times 10^{-8}\times 0.4082}{5.30\times 10^{-6}}=1.67\times 10^{-3}ohm$

Current is given i = 11 A

So emf $e=11\times 1.67\times 10^{-3}=0.0183volt$

Emf induced in the coil is $e=-\frac{d\Phi }{dt}=-A\frac{dB}{dt}$

$0.0183=5.30\times 10^{-6}\times \frac{dB}{dt}$

$\frac{dB}{dt}=3.466\times 10^3=T/sec$

8 0

2 years ago

calculate the distance a plane flies on a 7.95 hour flight from Chicago to London. Assume a constant speed of 800.0 km/h

soldier1979 [14.2K]

Answer:

6360 km

Explanation:

Use the kinematics equation $x=v_ot+\frac{1}{2}at^2$ . We are given t = 7.95 hours and a = 0 m/s^2 (constant speed means there is no acceleration). Solve for x.