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3 years ago

A car accelerates away from a stop sign. Is the work done negative or positive? Explain why.

Physics

1 answer:

erma4kov [3.2K]3 years ago

8 0

Answer:

positively

Explanation:

Because there is and absolute number so no matter the they accelerate backwards or forwards, they will still be traveling away at an positive number.

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A man has a weight of 100 Newtons. How much work is done if he climbs 4meters up a ladder?

Aliun [14]

Answer:

400 J

Explanation:

Work is done when a force that is applied to an object moves that object.

The work is calculated by multiplying the force by the amount of movement of an object

W = F * d

here the man has to work against the gravitational field. (against his weight)

F =100 N

Work done = F * d

= 100 * 4

= 400 J

7 0

4 years ago

Please help me fr fr !

Furkat [3]

The answer is A because it describes both toy cars

6 0

3 years ago

Aconstant current of 3 Afor 4 hours is required to charge an automotive battery. If the terminal voltage is V, where t is in hou

kirza4 [7]

Answer:

(a) 43.2 kC

(b) 0.012V kWh

(c) 0.108V cents

Explanation:

<u>Given:</u>

i = current flow = 3 A
t = time interval for which the current flow = $4\ h = 4\times 3600\ s = 14400\ s$
V = terminal voltage of the battery
R = rate of energy = 9 cents/kWh

<u>Assume:</u>

Q = charge transported as a result of charging
E = energy expended
C = cost of charging

Part (a):

We know that the charge flow rate is the electric current flow through a wire.

$\therefore i = \dfrac{Q}{t}\\\Rightarrow Q =it\\\Rightarrow Q = 3\times 14400\\\Rightarrow Q = 43200\ C\\\Rightarrow Q = 43.200\ kC\\$

Hence, 43.2 kC of charge is transported as a result of charging.

Part (b):

We know the electrical energy dissipated due to current flow across a voltage drop for a time interval is given by:

$E = Vit\\\Rightarrow E = V\times 3\times 4\\\Rightarrow E = 12V\ Wh\\\Rightarrow E = 0.012V\ kWh\\$

Hence, 0.012V kWh is expended in charging the battery.

Part (c):

We know that the energy cost is equal to the product of energy expended and the rate of energy.

$\therefore \textrm{Cost}=\textrm{Energy}\times \textrm{Rate}\\\Rightarrow C = ER\\\Rightarrow C = 0.012V\times 9\\\Rightarrow C =0.108V\ cents$

Hence, 0.108V cents is the charging cost of the battery.

4 0

4 years ago

What behavior of light proves that it is a wave? Hint: will this ONLY happen because light is a wave, or could it also be true o

kiruha [24]

It’s red shift and blue shift because This only occurs when the frequency of the wave is made longer or shorter due to the movement of the source relative to the observer

4 0

3 years ago

A force that tries to slow things down when two things are rubbed together

irakobra [83]

Answer:

Friction

Explanation:

friction is the force that tries to slow things down when two things are rubbed together.

5 0

3 years ago

Read 2 more answers