Answer:
The current lags the potential difference by π/2 in an inductor
Explanation:
The potential difference leads to the current by
. Alternate signals such as current and voltage -in this case- are periodic, this means that this signals are repeated at fixed spaces of time. Thus, In an inductor the current lags the potential difference by
.
displacement is given by equation

now at t = 5 s the position is

similarly position at t = 9 s

so the displacement of object in given interval of time will be

time interval

now the average velocity will be given as


so its average speed is 252 m/s
Answer:
Explanation:
On rubbing a glass rod with silk, the electrons from the glass rod get transferred to the silk. The silk now has an excess of electrons and so is negatively-charged. On the other hand, the glass rod is deficient in electrons and hence is positively-charged.
In the above case, the silk undergoes negative electrification.
Now, when the positively charged glass rod is touched on the disc of a negatively charged gold leaf electroscope, the electrons shifts towards rod, hence amount of charge on gold leaves decreases and the divergence between the gold leaves decreases as unlike charges attract each other.
Hence, the divergence decreases when a glass rod rubbed with silk is brought near the disc of negatively charged electroscope.
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Answer: 
Explanation:

where;
= final velocity = 0
= initial velocity = 60 km/h = 16.67 m/s
= acceleration
= distance
First all of, because acceleration is given in m/s and not km/h, you need to convert 60km/h to m/s. Our conversion factors here are 1km = 1000m and 1h = 3600s

Solve for a;

Begin by subtracting 

Divide by 2d

Now plug in your values:



If you're wondering why I calculated acceleration first is because in order to find force, we need 2 things: mass and acceleration.

m = mass = 900kg
a = acceleration = -2.78m/s

It's negative because the force has to be applied in the opposite direction that the car is moving.