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Tanzania [10]
3 years ago
7

You are in a speedboat on a river moving in the same direction as the current. The speedometer on the boat shows that its speed

is 20 km/h. However, a person on the shore measures the boat's speed as 23 km/h. How is this possible?
Physics
1 answer:
zloy xaker [14]3 years ago
5 0
From the reference point of the river, the speed of the boat is 20 km/h. From the reference point of someone standing on the shore, the speed of the boat is the speed on the speedometer plus the downstream speed of the current.
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the temperature of a 2.0-kg increases by 5*c when 2,000 J of thermal energy are added to the block. What is the specific heat of
nata0808 [166]
To calculate the specific heat capacity of an object or substance, we can use the formula

c = E / m△T

Where
c as the specific heat capacity,
E as the energy applied (assume no heat loss to surroundings),
m as mass and
△T as the energy change.

Now just substitute the numbers given into the equation.

c = 2000 / 2 x 5
c = 2000/ 10
c = 200

Therefore we can conclude that the specific heat capacity of the block is 200 Jkg^-1°C^-1
3 0
3 years ago
a spring gun initially compressed 2cm fires a 0.01kg dart straight up into the air. if the dart reaches a height it 5.5m determi
Vikki [24]

Answer:

2697.75N/m

Explanation:

Step one

This problem bothers on energy stored in a spring.

Step two

Given data

Compression x= 2cm

To meter = 2/100= 0.02m

Mass m= 0.01kg

Height h= 5.5m

K=?

Let us assume g= 9.81m/s²

Step three

According to the principle of conservation of energy

We know that the the energy stored in a spring is

E= 1/2kx²

1/2kx²= mgh

Making k subject of formula we have

kx²= 2mgh

k= 2mgh/x²

k= (2*0.01*9.81*5.5)/0.02²

k= 1.0791/0.0004

k= 2697.75N/m

Hence the spring constant k is 2697.75N/m

7 0
3 years ago
How much energy will be transferred to your eardrum while listening to this sound for 1.0 min?
Phoenix [80]

So E = 2x10^-3W/m^2*(π*(3.0x10^-3m)^2)*1min*60s... = 3.4x10^-6J

5 0
3 years ago
A small 0.14 kg metal ball is tied to a very light (essentially massless) string that is 0.9 m long. The string is attached to t
Vsevolod [243]

Answer:

a) v=2.743m/s

b) a_c = 8.363m/s^2

c) T=2.543N

Explanation:

First, calculate the height of the ball at the starting point:

y' = 0.9cos(55)

y' = 0.516

At this point, just in the moment the ball is released, all the energy of the system is potencial gravitational energy. When it is at the bottom all the potencial energy is transformed into kinetic energy:

E_p=E_k\\mgh=\frac{mv^2}{2}

Solving for v:

v=\sqrt{2gh}

if h is the height loss: (l-y')

v=2.743m/s

The centripetal acceleration is the acceleration caused by the tension force exercised by the string, and is pointing outside of the trayectory path (at the lowest point, directly dawn):

a_c=\frac{v^2}{r}

a_c = 8.363m/s^2

To calculate tension, just make the free body diagram of forces in the ball, noticing the existence of the centripetal acceleration:

\sum{F_y}=ma_c=T-W\\T=ma_c+W\\T=m(a_c+g)\\T=0.14(8.363+9.8)\\T=2.543N

4 0
4 years ago
The tower crane is used to hoist a 2.0mg- load upward at constant velocity. The 1.7Mg- jib BD and 0.6-Mg jib BC have centers of
Ksivusya [100]
This is a classic problem in statics. The counterweight is placed so that the tower crane would be stable, or the total moment is zero. There are four sources of torques: the load, the jib BD, the jib BC, and the counter weight. Staring with the total moment equals zero, and taking clockwise moments as positive. The units of moment here is Mg * m.

M = 0
(2.0)(12.5) + (1.7)(9.5) - (0.6)(4) - (C)(7.5) = 0
7.5C = 38.75
C = 5.17 Mg

Therefore, the counterweight must be 5.17 Mg.


I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!
3 0
3 years ago
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