1250 J in 5 sec= 250 Joule(s) per second (1250/5 0
250 Joules per second = 250 Watts ( 1J/s = 1 Watt per definition)
250 Watts output = 250/0.65 efficiency = 384 Watts input
1 Horsepower = 732 Watts
Motors 1 Horsepower and under are made in certain step sizes like
3/4 , 1/2 , 1/3, 1/4, 1/16 1/20 of a Horsepower.
3/4 Horsepower is 549 Watts
1/2 Horsepower is 366 Watts
so you need to 3/4 horsepower motor to achieve 1250 J of work in 5 seconds.
Period = 6 seconds and 
.
<u>Explanation:</u>
We have , the motion of a swing that requires 6 seconds to complete one cycle. Period is the amount of time needed to complete one oscillation . And in question it's given that 6 seconds is needed to complete one cycle. Hence ,Period of the motion of a swing is 6 seconds . Frequency is the number of vibrations produced per second and is calculated with the formula of 
. SI unit of frequency is Hertz or Hz. We know that time period is 6 seconds so frequency =
⇒ 
⇒ 
⇒
Therefore , Period = 6 seconds and .
Answer: The angle between force and displacement should be θ = 90° for minimum work. The angle between force and displacement should be θ = 0° for maximum work.
Forces are balanced when net force on the object is zero or the sum of all force on the object is zero.
For book kept on a shelf, the weight of the book in down direction is balanced by the normal force on the book by the shelf. hence the book kept on a shelf is an example of balanced force.
In case of air rushing out of balloon , the balloon experience a net force by the air coming out of it.
rolling over and falling off the bed , the object falls under gravity force.
a car speeding up accelerates. since it accelerates , it has net force on it.
Answer:
C.
Explanation:
Exothermic refers to a RELEASE of energy through a reaction(usually chemical). When salt dissociates, polar water molecules pull apart ions, releasing energy.
