All categories

3 years ago

A 60-kg woman runs up a staircase 15 m high (vertically) in 20 s.

Physics

1 answer:

erma4kov [3.2K]3 years ago

4 0

Answer:

(a) 441 W (b) 0.59 hP

Explanation:

Given that,

Mass of a woman, m = 60 kg

Height of a staircase, h = 15 m

Time, t = 20 s

(a) We need to find the power she expend. Work done per unit time is called power. It is given by :

$P=\dfrac{W}{t}\\\\P=\dfrac{mgh}{t}\\\\P=\dfrac{60\times 9.8\times 15}{20}\\\\P=441\ W$

( b) Since, 1 hP = 745.7 W

P = 0.59 hP

You might be interested in

What is shown in the diagram?

Sav [38]

Answer:

an electromagnet

Explanation:

4 0

2 years ago

What does it mean to say the mass is conserved during a physical change ?

Olin [163]

Mater doesn't just appear or disappeared. Chemical elements are still there just the connections and how it combines changes.

So what goes into your chemical eqation must still exist after the change.

4 0

3 years ago

Read 2 more answers

An electrical heater 100 mm long and 5 mm in diameter is inserted into a hole drilled normal to the surface of a large block of

slega [8]

Answer:

$T_{1}=94.9^{o}C$

Explanation:

Given data

length=100mm

Diameter=5mm

Thermal conductivity=5 W/m.K

Power=50 W

Temperature=25°C

The temperature of heater surface follows from the rate equation written as:

$T_{1}=T_{2}+\frac{q}{kS}$

Where S can be estimated from the conduction shape factor for a vertical cylinder in semi infinite medium

$S=\frac{2\pi L}{ln(\frac{4L}{D} )} \\$

Substitute the given values

$S=\frac{2\pi (0.1m)}{ln[\frac{4*0.1m}{0.005m} ]}\\ S=0.143m$

The temperature of heater is then:

$T_{1}=25^{o}C+\frac{50W}{5W/m.K*0.143m} \\T_{1}=94.9^{o}C$

The temperature reached by the heater when dissipating 50 W with the surface of the block at a temperature of 25°C.

$T_{1}=94.9^{o}C$

5 0

2 years ago

Medical x-rays, with a wavelength of about 10^(-10) m, can penetrate completely through your skin.

natulia [17]

Wavelength of X-rays = 10⁻¹⁰ m
Wavelength of UV = 1000 x 10⁻¹⁰
= 10⁻⁷ m

4 0

2 years ago

A 1.5-kg ball is throw at 10 m/s. What is the balls momentum?

alexdok [17]

Answer : The momentum of ball is, 15 kg.m/s

Explanation :

Momentum : It is defined as the motion of a moving body. Or it is defined as the product of mass of velocity of an object.

Formula of momentum is:

where,

p = momentum = ?

m = mass = 1.5 kg

v = velocity = 10 m/s

Now put all the given values in the above formula, we get:

Therefore, the momentum of ball is 15 kg.m/s

3 0

2 years ago