(a) 154.5 N
Let's divide the motion of the sprinter in two parts:
- In the first part, he starts with velocity u = 0 and accelerates with constant acceleration for a total time During this part of the motion, he covers a distance equal to , until he finally reaches a velocity of . We can use the following suvat equation:
which reduces to
(1)
since u = 0.
- In the second part, he continues with constant speed , covering a distance of in a time . This part of the motion is a uniform motion, so we can use the equation
(2)
We also know that the total time is 10.0 s, so
Therefore substituting into the 2nd equation
From eq.(1) we find
(3)
And substituting into (2)
Solving for t,
So from (3) we find the acceleration in the first phase:
And so the average force exerted on the sprinter is
b) 14.5 m/s
The speed of the sprinter remains constant during the last 55 m of motion, so we can just use the suvat equation
where we have
u = 0
is the acceleration
is the time of the first part
Solving the equation,
Answer:
Explanation:
Given
Frequency of whistle
Human hearing frequency
When a source or observer moves relative to each other then there is change in apparent frequency which is given by
where v=velocity of sound(340 m/s )
=velocity of observer
=velocity of source
=apparent frequency
=original Frequency
Answer:
You're answer should be series circuits are simpler than parallel circuits.
Explanation: I found this answer on the internet.
In series circuit, all the components are connected in single path of current flow.
If one part of the circuit breaks, complete circuit would break and all the other parts also would not operate.
The voltage is not same everywhere. It is different across each component.
In series circuit, net resistance is more as resistance of all the components connected in series are added up.
a = ( V2 - V1)/( t2 - t1)
3.2 = ( 23.5m/s - 15.2m/s)/(t - 0)
3.2m/s = 8.3/t
t(3.2) = 8.3
t = 8.3/3.2
t = 2.59 seconds