Answer:
The number of complete vibration or wave made in
one second is called frequency.
Part a
Answer: NO
We need to calculate the distance traveled once the brakes are applied. Then we would compare the distance traveled and distance of the barrier.
Using the second equation of motion:
where s is the distance traveled, u is the initial velocity, t is the time taken and a is the acceleration.
It is given that, u=86.0 km/h=23.9 m/s, t=0.75 s, 
Since there is sufficient distance between position where car would stop and the barrier, the car would not hit it.
Part b
Answer: 29.6 m/s
The maximum distance that car can travel is 
The acceleration is same,
The final velocity, v=0
Using the third equation of motion, we can find the maximum initial velocity for car to not hit the barrier:
Hence, the maximum speed at which car can travel and not hit the barrier is 29.6 m/s.
More work is done when one man lifts the weight using a pulley. Option C is correct.
<h3>What is mechanical advantage ?</h3>
Mechanical advantage is a measure of the ratio of output force to input force in a system, it is used to obtained efficiency of forces in levers and pulley.
It is an effective way of amplify the force in simple machines like lever The theoretical mechanical advantage is defined as the ratio of the force responsible for the useful work in the system to the applied force.
More work is done when one man lifts the weight using a pulley. With the pulley, the mechanical advantage is increasing.
Hence, option C is correct.
To learn more about the mechanical advantage, refer to the link;
brainly.com/question/7638820
#SPJ1
Then the waves (and the energy they carry) are completely reflected from the surface of the impenetrable medium.
Example:
An ordinary mirror is a sheet of glass with a thin layer of aluminum
or silver stuck to the back of the glass. Light waves have no trouble
traveling through the glass, but they can't get through the silver layer
on the back of it. So the waves completely bounce off of the silver, and
go back through the glass in the direction they came from.
24km/hour=(20/3)m/s
Hence, W=1/2*1168kg*[(20/3)/m/s]^2=25955.56J
