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Elenna [48]
3 years ago
10

A rock is dropped straight down from roof. It hits the ground with a velocity of 28.2 m/sec. How high was the roof, and how long

did it take to hit the ground?
Physics
1 answer:
notsponge [240]3 years ago
6 0

Answer:

18 secs

Explanation:

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A 15-lb block B starts from rest and slides on the 25-lb wedge A, which is supported by a horizontal surface. Neglecting frictio
xxTIMURxx [149]

The angle of the wedge is 30°.

Answer:

5.88 ft/s

Explanation:

a) The block will slide down due to it's weight.

initial velocity u= 0

final velocity, v

acceleration, a = g sin 30° = 32 ft/s²× sin 30° = 16 ft/s²

Sliding displacement, s = 3ft

Use third equation of motion:

v^2-u^2 = 2as

substitute the values and solve for v

v^2-0 = 2\times 16 \times 3 =96 ft^2/s^2\\v = 9.8 ft/s

b) Use conservation of momentum:

Initial momentum of the system  = 0

final momentum = (15) ( 9.8)+ (25)(v')

v' = 5.88 ft/s

3 0
3 years ago
A camcorder has a power rating of 15 watts. If the output voltage from its battery is 5 volts, what current does it use?
MrMuchimi

Formula

W = E * I

Givens

E = 5 volts

W = 15 watts

I = ?

Solution

W = E * I

15 = 5 * I

15/5 = I

I = 3 amps.   Answer

5 0
3 years ago
If an astronaut throws an object in space, the object’s speed will _____
BigorU [14]
The object's speed will not change.

In fact, after the astronaut throws the object, no additional forces will act on it (since the object is in free space). According to Newton's second law:
\sum F=ma
where the first term is the resultant of the forces acting on the body, m is the mass of the object and a its acceleration, we see that if no forces act on the object, then the acceleration is zero. Therefore, the acceleration of the object is zero, and its velocity remains constant.
7 0
4 years ago
Joanne drives her car at a speed of 20 m/s. when she applied her breaks, a frictional force of 2000 N brought her car to a compl
Papessa [141]

Answer:

A) 1000 kg

Explanation:

vf = vi + at

0 = 20 + (a)(10)

a = -2.0 m/s^2

F = ma

2000 = (m)(2)

m = 1000 kg

8 0
1 year ago
As a physics instructor hurries to the bus stop, her bus passes her, stops ahead, and begins loading passengers. She runs at 6.0
Alika [10]

velocity of the physics instructor with respect to bus

v = 6 m/s

acceleration of the bus is given as

a = 2 m/s^2

acceleration of instructor with respect to bus is given as

a = -2 m/s^2

now the maximum distance that instructor will move with respect to bus is given as

v_f^2 - v_i^2 = 2 a d

0 - 6^2 = 2(-2)(d)

-36 = - 4 d

d = 9 m

so the position of the instructor with respect to door is exceed by

\delta x = 9 - 6 = 3 m

so it will be moved maximum by 3 m distance

7 0
4 years ago
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