2. Only power tools with a 3-wire cord with

1. Which of the following is NOT a vector quantity? (a) Displacement. (b) Energy. (c) Force. (d) Momentum. (e) Velocity.

dem82 [27]

Answer:

B. energy

Explanation:

A vector has direction.

Energy does not have a direction.

5 0

3 years ago

A rocket takes off from Earth's surface, accelerating straight up at 47.2 m/s2. Calculate the normal force (in N) acting on an a

lions [1.4K]

Answer:

Approximately $4.61\times 10^{3}\; {\rm N}$ upwards (assuming that $g = 9.81\; {\rm m\cdot s^{-2}}$ .)

Explanation:

External forces on this astronaut:

Weight (gravitational attraction) from the earth (downwards,) and
Normal force from the floor (upwards.)

Let $(\text{normal force})$ denote the magnitude of the normal force on this astronaut from the floor. Since the direction of the normal force is opposite to the direction of the gravitational attraction, the magnitude of the net force on this astronaut would be:

$\begin{aligned}(\text{net force}) &= (\text{normal force}) - (\text{weight})\end{aligned}$ .

Let $m$ denote the mass of this astronaut. The magnitude of the gravitational attraction on this astronaut would be $(\text{weight}) = m\, g$ .

Let $a$ denote the acceleration of this astronaut. The magnitude of the net force on this astronaut would be $(\text{net force}) = m\, a$ .

Rearrange $\begin{aligned}(\text{net force}) &= (\text{normal force}) - (\text{weight})\end{aligned}$ to obtain an expression for the magnitude of the normal force on this astronaut:

$\begin{aligned}(\text{normal force}) &= (\text{net force}) + (\text{weight}) \\ &= m\, a + m\, g \\ &= m\, (a + g) \\ &= 80.9\; {\rm kg} \times (47.2\; {\rm m\cdot s^{-2}} + 9.81\; {\rm m\cdot s^{-2}}) \\ &\approx 4.61 \times 10^{3}\; {\rm N}\end{aligned}$ .

3 0

2 years ago

Cloudy nights are usually warm because

almond37 [142]

Answer:

When you have a cloudy night, the clouds prevent heat from escaping through the atmosphere and into space.

The clouds act like a blanket and trap the heat it, and that is why every time you have a cloudy night, it is always warmer than a clear night.

5 0

3 years ago

Compare and contrast the three classes of levers.

Xelga [282]

Class I . . .
The fulcrum is between the effort and the load.
The mechanical advantage may be any positive number, more or less than ' 1 '.

Class II . . .
The load is between the fulcrum and the effort.
The mechanical advantage is always greater than ' 1 '.

Class III . . .
The effort is between the fulcrum and the load.
The mechanical advantage is always less than ' 1 '.

7 0

3 years ago

How much voltage is required to run 0.42 A of current through a 150

igomit [66]

The voltage in the resistor is 63 V

Explanation:

We can solve the problem by applying Ohm's law, which states the relationship between voltage, current and resistance in a resistor:

$V=RI$