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3 years ago

what is haopening to the speed and acceleration as a car travels from rest to 72 km/hr in 4.0 seconds?

1 answer:

6 0

From the given information, we don't know. All we can tell is the net effect of all the changes during those 4 seconds ... the "averages".

The average change in speed is an increase of 72 km/hr (20 m/s) during that time.

The average acceleration is a constant 18 km/hr/sec (5 m/s^2) during the same time.

But both the speed and the acceleration may have gone up or down many times during the 4 seconds.

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Five 2.0-ω resistors are connected as shown in the figure. what is the equivalent resistance of this combination between points

Misha Larkins [42]

If resistors are connected in series then total resistance=2+2+2+2+2
=10 watt
if connected in parallel then total resistance,1/R=1/2+1/2+1/2+1/2+1/2
1/R=5/2
So R=2/5
R=0.4w

5 0

4 years ago

for a freely falling object dropped from rest, what is the acceleration at the end of the fifth second of fall?

lara31 [8.8K]

acceleration due to gravity is always 9.8 m/s/s (on earth)

3 0

3 years ago

What changes to landforms are caused by movements at transform boudaries

I am Lyosha [343]

Not much changes, but there are some great pressure so some hills may form.

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3 years ago

A student weighing 500. newtons

Romashka [77]

Answer:

The elevator must be <u>accelerating upward</u> as the net force acting is upward.

Explanation:

Given:

Original weight of the student, $W=500\ N$

Reading on the spring scale is the normal reaction by the scale on the student and is given as, $N=520\ N$

The normal reaction acts in the upward direction while the weight of the student acts vertically downward.

Now, the magnitude of the normal reaction is greater than the magnitude of the weight. Therefore, the net force acting on the student is given as:

$F_{net}=N-W\\F_{net}=520-500=20\ N(\textrm{Vertically upward})$

Therefore, the net force is acting vertically upward.

Now, as per Newton's second law, the direction of the net acceleration acting on a body is the same as the direction of the net force acting on it.

Thus, the elevator must be accelerating upward as the net force acting is upward.

6 0

3 years ago

A frictionless piston–cylinder device contains 7 kg of nitrogen at 100 kPa and 250 K. Nitrogen is now compressed slowly accordin

lora16 [44]

Answer: -1038.8 kJ

Explanation:

From the question, we can see that PV^n = constant. And as such, we can deduce that it is a polytropic process. Thus, we can use the polytropic work equation to calculate the needed work input.

from the question we were given

Mass of nitrogen, m = 7kg

initial temperature, T1 = 250k

Final temperature, T2 = 450k

Polytropic index, n = 1.4

Specific gas constant, R = 0.2968kJ/kgK

W = [p2 * v2 - p1 * v1] / 1 - n

W = [m * R * T2 - T1] / 1 - n

W = 7*0.2968*(450 - 250)] / 1 - 1.4

W = [7*0.2968*200] / -0.4

W = 415.52 / -0.4

W = -1038.8 kJ

5 0

3 years ago