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2 years ago

Please show the work and steps. The answer is (3.3 s, 15 m/s)

Physics

1 answer:

Anna [14]2 years ago

8 0

Answer:

t = 3.3 s and V = 15 m/s

Explanation:

Given that,

Distance covered by the car, d = 50 m

Initial speed, u = 5 m/s

Final speed, v = 25 m/s

Firstly we can find the acceleration of the car using third equation of motion. i.e.

$v^2-u^2=2as\\\\a=\dfrac{v^2-u^2}{2d}\\\\a=\dfrac{(25)^2-(5)^2}{2(50)}\\\\a=6\ m/s^2$

Let t is the time taken by the car to occur this.

$t=\dfrac{v-u}{a}\\\\t=\dfrac{25-5}{6}\\\\t=3.3\ s$

Let v is the average velocity of the car. It can be calculated as follows :

$V=\dfrac{u+v}{2}\\\\V=\dfrac{25+5}{2}\\\\V=\dfrac{30}{2}\\\\V=15\ m/s$

So, the time taken by the car to occur this is 3.3 seconds and the average velocity of the car is 15 m/s.

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(a) What is the intensity in W/m2 of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 500 J of en

inysia [295]

Answer:

4.42 x 10⁷ W/m²

Explanation:

A = energy absorbed = 500 J

η = efficiency = 0.90

E = Total energy

Total energy is given as

E = A/η

E = 500/0.90

E = 555.55 J

t = time = 4.00 s

Power of the beam is given as

P = E /t

P = 555.55/4.00

P = 138.88 Watt

d = diameter of the circular spot = 2.00 mm = 2 x 10⁻³ m

Area of the circular spot is given as

A = (0.25) πd²

A = (0.25) (3.14) (2 x 10⁻³)²

A = 3.14 x 10⁻⁶ m²

Intensity of the beam is given as

I = P /A

I = 138.88 / (3.14 x 10⁻⁶)

I = 4.42 x 10⁷ W/m²

6 0

2 years ago

Read 2 more answers

Three 7 0hm resistors are connected in series across a 10 V battery. What is the equivalent resistance of the circuit?

Tomtit [17]

Given

Three 7 ohm resistor are in series.

The battery is V=10V

To find

The equivalent resistance

Explanation

When the resistance are in series then the resistance are added to find its equivalent.

Thus the equivalent resistance is:

$R=7+7+7=21\Omega$

Conclusion

The equivalent resistance is 21 ohm

4 0

5 months ago

A gasoline tank has the shape of an inverted right circular cone with base radius 4 meters and height 5 meters. Gasoline is bein

RSB [31]

Answer:

h'=0.25m/s

Explanation:

In order to solve this problem, we need to start by drawing a diagram of the given situation. (See attached image).

So, the problem talks about an inverted circular cone with a given height and radius. The problem also tells us that water is being pumped into the tank at a rate of $8m^{3}/s$ . As you may see, the problem is talking about a rate of volume over time. So we need to relate the volume, with the height of the cone with its radius. This relation is found on the volume of a cone formula:

$V_{cone}=\frac{1}{3} \pi r^{2}h$

notie the volume formula has two unknowns or variables, so we need to relate the radius with the height with an equation we can use to rewrite our volume formula in terms of either the radius or the height. Since in this case the problem wants us to find the rate of change over time of the height of the gasoline tank, we will need to rewrite our formula in terms of the height h.

If we take a look at a cross section of the cone, we can see that we can use similar triangles to find the equation we are looking for. When using similar triangles we get:

$\frac {r}{h}=\frac{4}{5}$