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3 years ago

What happens when heat is transferred by convection

1 answer:

3 0

Convection is heat transfer by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying energy with it.

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a bike is moving with a velocity of 90km/hr.after applying break it stops in 5 sec. calculate the force applied by brakes .mass

pentagon [3]

Explanation:

initial velocity(u) = 90 km/s = 25 m/s

time (t) = 5 sec

mass (m) = 200 kg

final velocity (v) = 0 m/s

v = u + at

0 = 25 + a * 5

-25 = 5 a

-5 = a

Therefore acceleration = -5m/s²

Force = mass * acceleration

F = 200*-5

F = -1000 N

7 0

4 years ago

A convex lens has a focal length of 16.5 cm. Where on the lens axis should an object be placed in order to get a virtual, enlarg

alexandr402 [8]

Answer:

Object should be placed at a distance, u = 7.8 cm

Given:

focal length of convex lens, F = 16.5 cm

magnification, m = 1.90

Solution:

Magnification of lens, m = - $\frac{v}{u}$

where

u = object distance

v = image distance

Now,

1.90 = $\frac{v}{u}$

v = - 1.90u

To calculate the object distance, u by lens maker formula given by:

$\frac{1}{F} = \frac{1}{u}+ \frac{1}{v}$

$\frac{1}{16.5} = \frac{1}{u}+ \frac{1}{- 1.90u}$

$\frac{1}{16.5} = \frac{1.90 - 1}{1.90u}$

$\frac{1}{16.5} = \frac{ 0.90}{1.90u}$

u = 7.8 cm

Object should be placed at a distance of 7.8 cm on the axis of the lens to get virtual and enlarged image.

6 0

4 years ago

A 0.03 kg golf ball is hit off the tee at a speed of 34 m/s. The golf club was in contact with the ball for 0.003 s. What is the

Liula [17]

Answer:

The average force on ball by the golf club is 340 N.

Explanation:

Given that,

Mass of the golf ball, m = 0.03 kg

Initial speed of the ball, u = 0

Final speed of the ball, v = 34 m/s

Time of contact, $\Delta t=0.003\ s$

We need to find the average force on ball by the golf club. We know that the rate of change of momentum is equal to the net external force applied such that :

$F=\dfrac{\Delta p}{\Delta t}\\\\F=\dfrac{mv-mu}{\Delta t}\\\\F=\dfrac{mv}{\Delta t}\\\\F=\dfrac{0.03\ kg\times 34\ m/s}{0.003\ s}\\\\F=340\ N$

So, the average force on ball by the golf club is 340 N.

4 0

4 years ago

Need help on this please

Ratling [72]

question 2 answer is ALL OF THE ABOVE

question 3 answer is WARM AND MOIST.

8 0

3 years ago

PLEASE ANSWER THIS WILL MARK AS BRAINLIEST PLEASE PUT TRUE ANSWERS

SIZIF [17.4K]

Answer:

Explanation:

A is wrong bc best DNA will survive

B is wrong because organism adapt not only for food source but to be able to live in the environment as well

C is wrong because single celled organisms don't adapt

6 0

3 years ago