Answer:
t = 4.6 s
Explanation:
given,
initial velocity of the car = 23 m/s
declaration rate of car = 5 m/s²
final velocity of the car = ?
time taken to stop the car = ?
using equation of motion to solve the question
v = u + a t
v is final velocity
u is the initial velocity
0 = 23 - 5 t
we have used negative sign because there is deceleration
5 t = 23
t = 4.6 s
time taken to stop the car is equal to t = 4.6 s
Answer:
E) The net work done by the two forces is zero joules.
Explanation:
As the elevator is moving at a constant speed, it is the same as being stationary. The tension in the cable perfectly balances the gravitational force. Work done by gravity = mgh
Work done by the tension = -Th
where, T = tension force. The negative sign comes as the direction of T is opposite to the direction of g. As the elevator moves at a constant speed, the magnitude of the two forces must be equal. Therefore, the total work done,
W = (mg - T)h = 0
Answer: A,C,D,E are correct statements of an inductor
A. When an inductor and a resistor are connected in series with a DC battery, the current in the circuit is reduced to zero in one time constant.
C. An inductor always resists any change in the current through it.
D. When it is connected in a circuit, an inductor always resists having current flow through it.
E. Inductors store energy by building up charge.
We are asked to know the reason why magnetic dipole can be written as U = -m *B. The reason for this was that the negative sign is just showing or indicating the direction of the force. If it if negative, it means that the work done is opposite to the force field.
