SOLUTION is given in attachment below.
The hint is "constant speed".
If there is a net force on an object, what occurs to that object? F net = m*a.... It accelerates!
So, if the desk is going at a CONSTANT speed, what does that tell you about the acceleration? There is a change in speed.
Fnet = m*a Since a = 0 Fnet = 0
Fnet = sum of the force... reflect the direction of F as the positive direction. Sum of the forces in the direction of F = 0 0 = F - friction F = friction
So, if F = 800 N, then friction = 800 N in the opposite direction.
Answer:
Explanation:
The total energy of an electron in an orbit consists of two components
1 ) Potential energy which is - ve because the field is attractive
2) Kinetic energy which represents moving electron having some velocity.
Kinetic is always positive.
3 ) In an orbit , The magnitude of potential energy is twice that of kinetic energy. So if -2E is the value of potential energy E wil be the value of kinetic energy.
4 ) Total energy will become some of potential energy and kinetic energy
-2E + E = -E
5 ) So total energy becomes equal to kinetic energy with only sign reversed.
In the given case total energy is -0.28 eV . Hence kinetic energy will be +0.28 eV.
When kinetic energy is calculated as +.28 eV , the potential energy will be
- 2 x .28 or - 0.56 eV .
Explanation:
It is given that,
Mass of the ball, m = 0.06 kg
Initial speed of the ball, u = 50.4 m/s
Final speed of the ball, v = -37 m/s (As it returns)
(a) Let J is the magnitude of the impulse delivered to the ball by the racket. It can be calculated as the change in momentum as :
J = -5.24 kg-m/s
(b) Let W is the work done by the racket on the ball. It can be calculated as the change in kinetic energy of the object.
W = -35.1348 Joules
Hence, this is the required solution.
