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3 years ago

A ball is launched at 40m/s. find its speed at the half way up point.

1 answer:

6 0

Ek - kinetic energy
v2 - unknown speed
v1 - 40 m/s (initial speed)
Ek=1/2 mv^2
Ek in half way up is 1/2 Ek (with another V)
So, Ek in the beginning is Ek1= 1/2 mv1^2
and in half way Ek2=1/2 mv2^2
Ek1=2*Ek2
1/2 mv1^2 = 2* 1/2 mv2^2
1/2 v1^2 = v2^2
1/2 40^2 = v2^2
800 = v2^2
v2 = sqrt (800) = 28,3 m/s

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An electric model train is accelerated at a rate of 8 m/s^2 by a 12 N force? What is the

jok3333 [9.3K]

Answer:

m = 1.5 kg

Explanation:

Data:

Aceleration (a) = 8 m/s²
Force (F) = 12 N
Mass (m) = ?

Use formula:

$\boxed{m = \frac{F}{a}}$

Replace in the formula:

$\boxed{m = \frac{12N}{8\frac{m}{s^{2}}}}$

Equate the newtons:

$\boxed{m = \frac{12kg*\frac{m}{s^{2}}}{8\frac{m}{s^{2}}}}$

Simplify m/s²:

$\boxed{m = \frac{12kg}{8}}$

It divides:

$\boxed{m =1.5kg}$

What is the mass of the train?

The mass of the train is <u>1.5 kilograms.</u>

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3 years ago

Assume that the upward direction is positive and the downward direction is negative. What is the ball's velocity (in m/s) when i

LenaWriter [7]

The given question is incomplete. The complete question is as follows.

You throw a ball vertically upward, and as it leaves your hand, its speed is 26.0 m/s.

(a) How high (in m) does it rise above the level where it leaves your hand?

(b) How long (in s) does it take to reach its highest point?

(c) How long (in s) does the ball take to return to the level where it left your hand after it reaches its highest point?

(d) Assume that the upward direction is positive and the downward direction is negative. What is the ball's velocity (in m/s) when it returns to the level where it left your hand? (Indicate the direction with the sign of your answer.)

Explanation:

(a) For maximum height, the formula will be as follows.

$v^{2} = u^{2} + 2as$

a = $v^{2} - 2gh$

or, h = $\frac{v^{2}}{2g}$

= $\frac{(26)^{2}}{2 \times 9.8}$

= $\frac{676}{19.6}$

= 34.5 m/s

Hence, it rises 34.5 m/s above the level where it leaves your hand.

(b) Time to reach maximum height is as follows.

v = u + at

or, v - gt = 0

t = $\frac{v}{g}$

= $\frac{26}{10}$

= 2.6 sec

Therefore, it will take 2.6 sec to reach its highest point.

(c) Time taken by the ball to ascent is equal to the time it has taken to descent.

Therefore, time taken by the ball to return to the level where it left your hand after it reaches its highest point? is also 2.6 sec.

(d) Speed of the ball will be 26 m/s in the downward direction. Hence, the velocity will be -26 m/s.

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3 years ago

Define second class lever

Aleks04 [339]

Answer:

Please find detailed explanation of second class levers below

Explanation:

Levers are one of the classes of machine that possesses three levels namely: first class, second class and third claas. A second class lever is the level of levers in which the load (L) is in between the pivot (F) and the effort (E).

Examples of second class levers include; wheelbarrow, a bottle opener etc. In the bottle opener for example, the bottle lid (load) is in between the pivot of the opener and the hand opening it (effort).

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3 years ago

As 390 g of hot milk cools in a mug, it transfers 30,000 J of heat to the environment. What is the temperature change of the mil

svetoff [14.1K]

We will apply:
Q = mcΔT; where Q is the heat, m is the mass, c is the specific heat capacity and ΔT is the temperature change.

30,000 = 390 x 3.9 x ΔT
ΔT = 19.7 °C

The temperature change is of 19.7 °C.

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3 years ago

How many poles do you expect to see in your magnet? Look around your room. Make a list of 5 items that might be attracted to the

jeyben [28]

Answer:

1.1 Two poles: North and South Poles.

1.2 - Staple pin - Nail - Tip of my phone charger - Metal keys - Cloth Hanger

1.3 - Wooden bed cot - Plastic pen - Game pad - Wooden shelf - Paper - A T-shirt

1.4 Yes

1.5 No

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3 years ago