A force of 6 N acts horizontally on a stationary mass of 2 kg for 4 s. The kinetic energy in Joule is:
Correct answer: B. 144
- A. 12
- B. 144
- C. 72
- D. 48
Explanation
To determine the kinetic energy of the mass after 4 seconds, apply Newton's second law. Given that the force (F) is 6 N and the mass (m) is 2 kg, we first find the acceleration (a) using F = ma, resulting in a = 3 m/s².Initially, the object is stationary, so the initial velocity (u) is 0. The final velocity (v) can be calculated using v = u + at, where t is 4 seconds, giving v = 12 m/s.Now, calculate the kinetic energy (KE) using the formula KE = 1/2 mv². Substituting the values, KE = 1/2 × 2 × (12)² = 144 J.The other options are incorrect due to either a miscalculation of velocity or an incorrect application of the kinetic energy formula.
This question appeared on the ETEA MDCAT 2012 paper, which you can sit online with every answer explained.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Kinetic Energy
Kinetic energy is the energy of motion, given for a nonrelativistic object by K = ½mv², so it depends on mass and the square of speed. Questions connect kinetic energy with work through the work energy theorem, calculate changes in kinetic energy, and distinguish it from momentum and potential energy.
Practise Work and Energy
748 free Work and Energy MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Kinetic Energy questions
Two bodies with masses m1 ans m2 have equal kinetic energies. If M1 and M2 are their respective momentum then the ratio between M1 and M2 is:
A particle of mass m at rest is acted upon by a force P for time t. Its kinetic energy is:
A disc at rest without slipping, rolls down a hill of height (3 x 9.8) m. What is its speed in m/sec when it reaches the bottom?
If the momentum of a body decreases by 20% the percentage decrease in K.E will be:
A 6.0-kg block is released from the rest 80m above the ground. When it has fallen 60m its kinetic energy is approximately:
Two objects, P and Q have the same momentum. Q has more kinetic energy than P if it: