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olchik [2.2K]
3 years ago
7

a car advertisement states that a certain car can accelerate from rest to 70km/h in 7 seconds. find the cars acceleration

Physics
1 answer:
ELEN [110]3 years ago
4 0
<span>a = (v2 - v1)/t= acceleration formula

a = (70 - 0)/7
a = 10 km/hr/sec
-----
It's better to use as few units as possible.
10 km/hr = 10 km*1000 m/km/(1 hr*3600 sec/hr) = 25/9 m/sec
a= 25/9 m/sec/se</span>
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Which two factors does the power of a machine depend on?
lianna [129]

The power of a machine depend on two factors are work and time.

Option C

<u>Explanation:</u>

In science, power defined as the amount of work done in a unit time. i.e. delivering work in a rate of time or energy supply, expressed in input of work or transmitted energy divided by the time interval (t) or W/t.

Example: Some work can be done in the long run with a low-power engine or in a short time with a motor with high performance. The equation for power can be given as

              Power\ (in\ watts) =\frac{\text { work (joules) }}{\text { time (seconds) }}

              P=\frac{W}{t}

7 0
3 years ago
A mother and daughter are on a seesaw in the park. How far from the center must the 160.9lb mother sit in order to balance the 6
Soloha48 [4]

Answer:

The mother has to sit 2.17 ft from the center on the other side of the seesaw.

Explanation:

We are trying to find the sum of torques given by the weights of mother and daughter to be zero.

If the torque of the daughter on one side of the pivoting point is given by:

5.5 ft x 63.5 lb x g = 349.25 g ft lb

we need that the absolute value of the torque exerted by the mom (160.9 lb) to be the same in magnitude (and of course opposite direction). So we assume that "d" is the distance at which the mother locates to make this torque equal in magnitude to her daughter's torque:

d x 160.9 lb x g = 349.25 g ft lb

d = 2.17 ft

3 0
3 years ago
A power plant produces 1000 MW to supply a city 40 km away. Current flows from the power plant on a single wire of resistance 0.
nikitadnepr [17]

Answer:

Current = 8696 A

Fraction of power lost = \dfrac{80}{529} = 0.151

Explanation:

Electric power is given by

P=IV

where I is the current and V is the voltage.

I=\dfrac{P}{V}

Using values from the question,

I=\dfrac{1000\times10^6 \text{ W}}{115\times10^3\text{ V}} = 8696 \text{ A}

The power loss is given by

P_\text{loss} = I^2R

where R is the resistance of the wire. From the question, the wire has a resistance of 0.050\Omega per km. Since resistance is proportional to length, the resistance of the wire is

R = 0.050\times40 = 2\Omega

Hence,

P_\text{loss} = \left(\dfrac{200000}{23}\right)^2\times2

The fraction lost = \dfrac{P_\text{loss}}{P}=\left(\dfrac{200000}{23}\right)^2\times2\div (1000\times10^6)=\dfrac{80}{529}=0.151

3 0
3 years ago
Include units with all of your answers. A 1.84 kg bucket full of water is attached to a 0.76 m long string.
aleksandrvk [35]
<span>c. What is the magnitude of the tension in the string at the bottom of the circle if you are swinging it at 3.37 m/s? </span>
7 0
3 years ago
If the coefficient of static friction is 0.357, and the same ladder makes a 58.0° angle with respect to the horizontal, how far
zavuch27 [327]

Answer: d= 0.57* l

Explanation:

We need to check that before ladder slips the length of ladder the painter can climb.

So we need to satisfy the equilibrium conditions.

So for ∑Fx=0, ∑Fy=0 and ∑M=0

We have,

At the base of ladder, two components N₁ acting vertical and f₁ acting horizontal

At the top of ladder, N₂ acting horizontal

And Between somewhere we have the weight of painter acting downward equal to= mg

So, we have N₁=mg

and also mg*d*cosФ= N₂*l*sin∅

So,

d=\frac{N2}{mg}*l * tan∅

Also, we have f₁=N₂

As f₁= чN₁

So f₁= 0.357 * 69.1 * 9.8

f₁= 241.75

Putting in d equation, we have

d= \frac{241.75}{69.1*9.8} *l * tan 58

d= 0.57* l

So painter can be along the 57% of length before the ladder begins to slip

3 0
3 years ago
Read 2 more answers
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