Answer:
b) 18 m/s is the correct answer.
Explanation:
initial velocity(u) = 30m/s
acceleration(a) = -4m/s²
time(t) = 3 seconds
final velocity(v) = ?
using the formula,
a = (v-u)/t
or, -4 = (v-30)/3
or, -12 = v-30
or, v = -12+30
so, v = 18 m/s
Best Answer: You need a reference point because all motion is defined relative to a point which is taken to be fixed. For example, when you say that a car is moving at 20 m/s, you mean that it's moving at 20 m/s relative to the ground, which you assume to be a fixed point. However, you also know that the ground (and the Earth) are really zipping through space at high speed as we orbit the Sun. If you want to define the car's speed relative to the Sun, you have to take the Earth's motion into account as well. Whenever you define the motion of an object on or above Earth, it's usually understood that the ground if your reference point. If it's not, you should specify another point.
Speed is a scalar quantity, which means that it only tells you how fast an object is moving. Velocity is a vector quantity: it tells you how fast an object is moving AND in what direction. For example, I might say that a car is moving at 20 m/s. That's the car's speed. But if I say that the car is moving at 20 m/s NORTH, then I've given you its velocity.
In velocities, direction can be given in several different ways:
(A) As a positive or negative sign. Example: The rocket is moving at +250 m/s. In this case, we've defined "up" as the positive direction and "down" as the negative direction.
(B) As an angle or compass heading. Example: The plane took off at 100 m/s 20º above the horizontal OR the car is driving at 30 m/s due west.
Sneaky question.
The secondary voltage will be zero.
Secondary voltage is the result of CHANGES in the primary voltage. That means the primary is energized with AC. The transformer in this question is energized with DC, which doesn't change. So there is no secondary voltage, this transformer doesn't work, and what you get out of it is: Smoke !
Answer:
the change in potential energy is proportional to the displacement from the equilibrium position.
Explanation:
Simple Harmonic Motion is said to occur when an object is oscillating around a particular position where is it in equilibrium by a force with the following features:
The force has to be directed towards the equilibrium position and secondly, the magnitude of the force is proportional to the displacement from the equilibrium position of the object.
Answer:
It is producing either a 435-Hz sound or a 441-Hz sound.
Explanation:
When two sound of slightly different frequencies interfere constructively with each other, the resultant wave has a frequency (called beat frequency) which is equal to the absolute value of the difference between the individual frequencies:
(1)
In this problem, we know that:
- The frequency of the first trombone is
- 6 beats are heard every 2 seconds, so the beat frequency is
If we insert this data into eq.(1), we have two possible solutions for the frequency of the second trombone: