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3 years ago

A man walks 30 m to the west, then 5 m to the east in 45 seconds. What is his average speed?

1 answer:

3 0

The displacement is the distance from the beginning point to the ending point. The time was just to throw you off. If he walks 30m due west, and then 5m due east, his displacement would be 30-5=25m to the west.

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A minivan is tested for acceleration and braking. In the street-start acceleration test, the elapsed time is 8.6 s for a velocit

Varvara68 [4.7K]

The question is incomplete. Here is the complete question:

A minivan is tested for acceleration and braking. In the street-start acceleration test, the elapsed time is 8.6 s for a velocity increase from 10 km/h to 100 km/h. In the braking test, the distance traveled is 44 m during braking to a stop from 100 km/h. Assume constant values of acceleration and deceleration. Determine

(a) the acceleration during the street-start test,

(b) the deceleration during the braking test.

Answer:

(a) 37500 km/h²

(b) 113636.36 km/h²

Explanation:

part (a)

Because it is given that we can assume constant acceleration therefore we can use the following equation of motion:

v = u + (a)(t)

where v is final velocity, u is initial velocity, a is acceleration and t is time change

Given in the question:

v = 100km/h

u = 10 km/h

t = 8.6 sec (changing to hours)

t = 0.0024 hours (round off to 4 decimal places)

100 = 10 + (a x 0.0024)

Rearranging the equation to find value of a

a = (100 – 10) / 0.0024

a = 37500 km/h² (Answer)

part (b)

Now we can use the following equation to find deceleration

2(a)(s) = v² – u²

Where a is acceleration, s is distance travelled, v is final velocity and u is initial velocity

Given in the question

s = 44 m

changing to km

s = 0.044 km

v = 0 km/h (because it stops)

u = 100 km/h

2(a)(0.044) = (0)² – (100)²

0.088(a) = 0 - 10000

a = - 10000/0.088

a = - 113636.36 km/h2

The negative sign in the answer shows that it is deceleration

Therefore deceleration = 113636.36 km/h² (Answer)

6 0

3 years ago

Explain in your own words the interaction between the electric and magnetic fields that make up a light wave.

iVinArrow [24]

Answer:

They oscillates perpendicularly to one another, the oscillation of one field generates the other field.

Explanation:

In a light wave, an oscillating electric field of a light wave produces a magnetic field, and the magnetic field also oscillates to produce an electric field. The magnetic field and the electric field of a light wave both oscillates perpendicularly to one another. The resultant energy and direction of the wave generated as a result of these oscillating fields is propagated perpendicularly to both fields.

8 0

3 years ago

A cart is loaded with a brick and pulled at constant speed along an inclined plane to the height of a seat-top. If the mass of t

grandymaker [24]

Answer:

13.23J

Explanation:

PE = m*g*h

PE = (3 kg ) * (9.8 m/s/s) * (0.45 m)

3 0

3 years ago

Read 2 more answers

If you quadruple the temperature of a black body, by what factor will the total energy radiated per second per square meter incr

arlik [135]

In modern physics, as it was called "Stefan-Boltzmann law", the total energy radiated per unit surface area of a black body is directly proportional to the fourth power of the black body's temperature T

as:

$P\alpha T^4$