5 numerical on energy
Answers
I hope it's helpful please mark me as brainliast.
1. A force of 10N causes a displacement or 2m in a body in its own direction. Calculate the work done by force. 20j
Solution: the work done by force = F x S = 10 N x 2m = 20 J
2. How much force is applied on the body when 150 joule of work is done in displacing the body through a distance of 10m in the direction of force?(15 N)
Solution: W = F x S Þ F = w/s = 150/10 = 15 N
3. A body of 5kg raised to 2m find the work done(98j)
Solution: T he work done to raise a body = PE = mgh = 5kg x 9.8 x 2 = 98 joule
4. A work of 4900j is done on road of mass 50 kg to lift it to a certain height. Calculate the height through which the load is lifted. (10m)
Solution: work done on road to lift = mgh Þ 4900 = 50 x 9.8 h Þ h = 10m
5. An engine work 54,000J work by exerting a force of 6000N on it. What is the displacement of the force . (9m)
Solution: S = W/F = 54,000J/6000N = 9m
6. A force of 10N acting on a body at an angle of 60 deg. with the horizontal direction displaces the body through a distance of 2m along the surface of a floor. Calculate the work done.
Now let the force or pulling act on the body makes an angle of 30 deg. with the horizontal. What is the value of the force to displace the body through 2m along the surface of the floor? (Cos 60 =1/2. and Cos 30 = √3/2) [ ans. 10 J, 10√3 N]
Solution: w = F S cos Q = 10 x 2 x Cos 60 = 20 x ½ = 10 N
w = F S cos Q = 10 x 2 x Cos 30 = 20 x √3/2 = 10√3 N
7. A force of 5N acting on body at angle of 30 deg. with the horizontal direction displace it horizontally through of distance of 6 m . Calculate the work done. (15√3 J)
Solution: w = F S cos Q = 5 x 6 x √3/2 = 15√3 J
8. A body of mass 2kg is moving with a speed of 20m/s Find the kinetic energy. (400J)
Solution: KE = 0.5 mv^2 = 0.5 x 2 x 20 x 20 = 400 J
9. A moving body of 30kg has 60 J of KE. Calculate the speed.
Solution: KE = 0.5 mv^2 Þ 60 = 0.5 x 30 x v^2
Þ 60 = 15 v^2 Þ 60/15Þ V = 2m/s
10. A hammer of mass 1kg falls freely from a height of 2 m .Calculate (I) The velocity and (II) The KE. of the hammer just before it touches the ground. Does the velocity of hammer depend on the mass of hammer? (6.29m-2 , 19.6 J )
Solution: PE = mgh = 1 x 9.8 x 2 = 19.6 j
Answer: ok
----------------------------------------------------------------------------------------------------------------
Question 1.
A light and a heavy object have the same momentum. Find out the ratio of their kinetic energies. Which one has a larger kinetic energy?
Question 2.
An object with 100 N weights is raised to a height of 15m. Find the potential energy possessed by the object at that height. Also find the new potential energy:
a.If the same object is raised half of its original height.
b.If the same object is raised to three times of its original height?
Given g=10m/s2
Question 3.
Define one joule of kinetic energy?
Question 4.
A ball of mass 2kg is thrown up with a speed of 10m/s. find the kinetic energy of the ball at the time of throwing. Also find the potential energy of the ball at the highest point?
Question 5.
An object of mass m and velocity v has kinetic energy= 200J. Find the new kinetic energy if the mass of the object becomes double and velocity still remains the same?