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3 years ago

How much potential energy does a 50-N box have when lifted at a height of 1.5M?

Physics

1 answer:

nikitadnepr [17]3 years ago

3 0

The correct answer is: Option (A) 75 J

Explanation:

First, be careful with the units here. As you can see it is mentioned that there is a 50N box. It means that the weight (mg) of the box is given as the unit is Newton, not its mass (which is in kg).

As,

Potential-energy = mass * acceleration-due-to-gravity * height

PE = m*g*h --- (A)

In equation (A), mg is actually the weight of the box, which is given.

mg = 50N

h = height = 1.5m

Plug the values in equation (A):

PE = 50 * 1.5 = 75 J (Option A)

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A 34-kg child on an 18-kg swing set swings back and forth through small angles. If the length of the very light supporting cable

kompoz [17]

Answer:

4.44s

Explanation:

A 34-kg child on an 18-kg swing set swings back and forth through small angles. If the length of the very light supporting cables for the swing is 4.9 m, how long does it take for each complete back-and-forth swing? Assume that the child and swing set are very small compared to the length of the cables

since the mass of the child and that of the swing is negligible, the masses wont be involved in the calculation

T=2π√L/g

g=acceleration due to gravity which is 9.81m/s2

the length of the supporting cable is 4.9m

T the period

period is the time required to make a complete oscillation

T=2*π√4.9/9.81

T=2*π*0.706

T=4.44s

4.44s

5 0

3 years ago

A T-shirt cannon can shoot a 0.085 kg T-shirt at nearly 30 m/s. The T-shirt cannon has a mass of 33 kg. If the initial net momen

IgorLugansk [536]

Answer:

Approximately $0.077\; {\rm m\cdot s^{-1}}$ (assuming that external forces on the cannon are negligible.)

Explanation:

If an object of mass $m$ is moving at a velocity of $v$ , the momentum $p$ of that object would be $p = m\, v$ .

Momentum of the t-shirt:

$\begin{aligned} p(\text{t-shirt}) &= m(\text{t-shirt}) \, v(\text{t-shirt}) \\ &= 0.085\; {\rm kg} \times 30\; {\rm m \cdot s^{-1}} \\ &= 2.55 \; {\rm kg \cdot m \cdot s^{-1}} \end{aligned}$ .

If there is no external force (gravity, friction, etc.) on this cannon, the total momentum of this system should be conserved. In other words, if $p(\text{cannon})$ denote the momentum of this cannon:

$p(\text{t-shirt}) + p(\text{cannon}) = 0$ .

$p(\text{cannon}) = -p(\text{t-shirt}) = -2.55\; {\rm kg \cdot m \cdot s^{-1}}$ .

Rewrite $p = m\, v$ to obtain $v = (p / m)$ . Since the mass of this cannon is $m(\text{cannon}) = 33\; {\rm kg}$ , the velocity of this cannon would be:

$\begin{aligned} v(\text{cannon}) &= \frac{p(\text{cannon})}{m(\text{cannon})} \\ &= \frac{-2.55\; {\rm kg \cdot m \cdot s^{-1}}}{33\; {\rm kg}} \\ &\approx 0.077\; {\rm m \cdot s^{-1}}\end{aligned}$ .

8 0

1 year ago

A train travels 57 kilometers in 3 hours, and then 87 kilometers in 2 hours. What is its average speed? km/hr

skad [1K]

Average speed (v) = total distance(d) / total time (t)
d = 57 + 87km = 144km
t = 2 + 3hrs = 5hrs
v = d÷t = 144÷5 = 28.8km/hr

3 0

2 years ago

I need help on my physics homework number 2

Mademuasel [1]

If it's in motion in the bottom it's called kinetic energy. Which means energy in motion

5 0

2 years ago

Which of the following elements is considered to be a non-metal?

ryzh [129]

Answer:Hydrogen (sometimes)

Carbon

Nitrogen

Oxygen

Phosphorus

Sulfur

Selenium

Fluorine

Chlorine

Bromine

Iodine

Astatine

Tennessine (sometimes considered a halogen or metalloid)

Helium

Neon

Argon

Krypton

Xenon

Radon

Oganesson (possibly behaves as a "noble gas", except it won't be a gas under ordinary conditions)

Explanation:

6 0

2 years ago