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Trava [24]
3 years ago
15

How much time is needed to produce 720 joules of work if 90 watts of power is used

Physics
1 answer:
Sladkaya [172]3 years ago
4 0

Answer:

8 seconds

Explanation:

power (P) is defined as the rate at which work is done.

power is measured in Watts (W) , when the work done is measured in Joules (J) and time in seconds

by the definition of power,

power=\frac{work.done}{time}\\ time=\frac{work.done}{power}\\ =\frac{720J}{90W} \\=8 seconds

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A rubber ball is dropped from a height of 8m. After strikingthe floor, the ball bounces to a height of 5m. a. If the ball had bo
kifflom [539]

Answer:

a) This means the collision between the ball and the floor is elastic.

b) This points to a perfectly inelastic collision between the ball and the floor as they stick together after collision

c) Check Explanation.

Explanation:

Collision of bodies are analysed according to whether both momentum and kinetic energy of the system is conserved, that is, if these two quantities before collision are equal to their values after collision.

In all types of collisions, momentum is usually conserved, but kinetic energy is conserved only in an elastic collision.

A ball dropped from a height of 8 m bounces up back to a height of 5 m.

a. If the ball had bounced to a height of 8m, how would you describe the collision between the ball and the floor?

The ball not bouncing back to a height of 8 m shows energy loss at some point in the total motion of the ball (most likely at the collision). If kinetic energy was conserved, the ball would bounce back up to the height at which it fell from (8 m) after the collision with the floor.

b. If the ball had not bounced at all, how would you describe the collision between the ball and the floor?

If the ball had not bounced at all, this means it lost all of its kinetic energy to the floor, and this points to a perfectly inelastic collision between the ball and the floor as they stick together after collision.

c. What happened to the energy lost by the ball during thecollision?

The energy lost during the collision is converted to another form, most likely responsible for some deformation on the ball & a minute deformation on the floor, converted to some form of heat as a result of the collision or into sound energy, usually, it's a combination of all This!

Hope this Helps!!!

5 0
4 years ago
A car is moving at 6 m/s and then accelerates at 1.7 m/s2 for 4.2 seconds. What is the final velocity of the car?
Bad White [126]

Explanation:

Hey there!!

Here,

Initial velocity (u) = 6m/s.

Acceleration (a) = 1.7m/s^2.

Time (t) = 4.2s.

final velocity (v) = ?

We have,

a =  \frac{v - u}{t}

Putting their values,

1.7 =  \frac{v - 6}{4.2}

7.14 = v - 6

v = 7.14 + 6

Therefore, the final velocity is 13.14 m/s.

<em><u>Hope</u></em><em><u> </u></em><em><u>it helps</u></em><em><u>.</u></em><em><u>.</u></em><em><u>.</u></em><em><u>.</u></em>

5 0
3 years ago
Consider the case of the car starting at rest and accelerating forward. A. Since the air inside the car is not leaking out, it m
Alchen [17]

Answer:

The force originates from the tires. Tires accelerate the car. The car interior in turn accelerates the air inside the car by providing a pushing force. Thus it is the car read windows, seats and side windows that push the air forward causing it to accelerate.

Explanation:

The air inside the car is being forced forward by the car interior. This includes the rear windows, seats, side windows etc.

This accelerating force originates from the tires, and makes the car interior accelerate with the car. The air inside (since it has no direct connection to the tires) is then pushed forward by the windows, seats etc.

7 0
3 years ago
1. What are the three ways an object can accelerate?
solong [7]

Answer:

increase speed, decrease speed, and change direction

Explanation:

4 0
3 years ago
An electric heater draws a steady 15.0A on a 120-V
morpeh [17]

Answer:

1. 1800 W

2. $ 17.3

Explanation:

From the question given above, the following data were obtained:

Current (I) = 15 A

Voltage (V) = 120 V

Time (t) = 20 h per day

Duration = 31 days

Cost = 15.5 cents per kWh

1. Determination of the power.

Current (I) = 15 A

Voltage (V) = 120 V

Power (P) =?

P = IV

P = 15 × 120

P = 1800 W

Thus, 1800 W of power is required.

2. Determination of the cost per month (31 days).

We'll begin by converting 1800 W to KW.

1000 W = 1 KW

Therefore,

1800 W = 1800 W × 1 KW / 1000 W

1800 W = 1.8 KW

Next, we shall determine the energy consumption for 31 days. This can be obtained as follow:

Power (P) = 1.8 KW

Time (t) = 2 h per day

Time (t) for 31 days = 2 × 31 = 62 h

Energy (E) =?

E = Pt

E = 1.8 × 62

E = 111.6 KWh

Finally, we shall determine the cost of consumption. This can be obtained as follow:

1 KWh = 15.5 cents

Therefore,

111.6 KWh = 111.6 KWh × 15.5 cents / 1 KWh

111.6 KWh = 1729.8 cents

Converting 1729.8 cents to dollar, we have:

100 cents = $ 1

Therefore,

1729.8 cents = 1729.8 cents × $ 1 / 100 cents

1729.8 cents = $ 17.3

Thus, it will cost $ 17.3 per month to run the electric heater.

4 0
3 years ago
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