which best describes the difference between speed and velocity? A) velocity is instantaneous ,B) speed is a vector quantity

When a 5.0 kg box is hung from a spring, the spring stretches to 50 mm beyond its relaxed length. (a) In an elevator acceleratin

Shtirlitz [24]

Answer:

a) the spring will stretch 60.19 mm with the same box attached as it accelerates upwards

b) spring will be relaxed when the elevator accelerates downwards at 9.81 m/s²

Explanation:

Given that;

Gravitational acceleration g = 9.81 m/s²

Mass m = 5 kg

Extension of the spring X = 50 mm = 0.05 m

Spring constant k = ?

we know that;

mg = kX

5 × 9.81 = k(0.05)

k = 981 N/m

a)

Given that; Acceleration of the elevator a = 2 m/s² upwards

Extension of the spring in this situation = X1

Force exerted by the spring = F

we know that;

ma = F - mg

ma = kX1 - mg

we substitute

5 × 2 = 981 × X1 - (5 ×9.81 )

X1 = 0.06019 m

X1 = 60.19 mm

Therefore the spring will stretch 60.19 mm with the same box attached as it accelerates upwards

B)

Acceleration of the elevator = a

The spring is relaxed i.e, it is not exerting any force on the box.

Only the weight force of the box is exerted on the box.

ma = mg

a = g

a = 9.81 m/s² downwards.

Therefore spring will be relaxed when the elevator accelerates downwards at 9.81 m/s²

6 0

2 years ago

Suppose a soccer ball is kicked from the ground at an angle 20.0º above the horizontal at 8.00 m/s. The y-velocity is determined

julia-pushkina [17]

initial speed of the ball by which it is kicked is 8 m/s

now the angle at which it is kicked is 20 degree

here we will have

$v_y = v sin20$

$v_y = 8 sin20 = 2.74 m/s$

now we will have

$\Delta y = v_y t + \frac{1}{2}at^2$

so if the ball again land on the ground at same level then we have

$\Delta y = 0$

$0 = 2.74 t - \frac{1}{2}(9.8) t^2$

$0 = 2.74 - 4.9 t$

$t = 0.56 s$

so total time will be 0.56 s

8 0

3 years ago

A device that uses electricity and magnetism to create motion is called a _________motor,magnet,generator . In a reverse process

lawyer [7]

A device that uses electricity and magnetism to create motion is called a "Motor" (which converts electric energy into mechanical energy) & <span>In a reverse process, a device that uses motion and magnetism can be used to create "Electromagnetism".

In short, 1st Blank = Motor
2nd Blank = Electromagnetism

Hope this helps!</span>

5 0

2 years ago

Read 2 more answers

. 30

schepotkina [342]

Answer:

Explanation:

Length if the bar is 1m=100cm

The tip of the bar serves as fulcrum

A force of 20N (upward) is applied at the tip of the other end. Then, the force is 100cm from the fulcrum

The crate lid is 2cm from the fulcrum, let the force (downward) acting on the crate be F.

Using moment

Sum of the moments of all forces about any point in the plane must be zero.

Let take moment about the fulcrum

100×20-F×2=0

2000-2F=0

2F=2000

Then, F=1000N

The force acting in the crate lid is 1000N

Option D is correct

7 0

2 years ago

1 6. Which of the following astronomical units is c/osest to the distance of the earth to the sun?

Ganezh [65]

Answer:

astronomical unit

Explanation:

https://en.wikipedia.org/wiki/Astronomical_unit

6 0

3 years ago