All categories

3 years ago

If a force does a positive amount of work on an object, does the object's speed

Physics

1 answer:

Alexxandr [17]3 years ago

8 0

The speed of the object increases

Explanation:

We can answer this question by applying the work-energy theorem, which states that the work done on an object is equal to the change in kinetic energy of the object. Mathematically:

$W=K_f -K_i= \frac{1}{2}mv^2-\frac{1}{2}mu^2$

where

W is the work done on the object

$K_f, K_i$ are the final and initial kinetic energy of the object, respectively

m is the mass of the object

v is its final speed

u is its initial speed

In this case, the force does a positive amount of work on the object, so

$W>0$

This also implies that

$K_f > K_i$

And so

$\frac{1}{2}mv^2 > \frac{1}{2}mu^2$

And therefore

$v>u$

which means that the speed of the object increases.

Learn more about work:

brainly.com/question/6763771

brainly.com/question/6443626

#LearnwithBrainly

You might be interested in

What is the mass of 3 m3 of a substance having density 1200 kg/m3

adell [148]

Answer:

3600 kg

Explanation:

From the question,

Density = Mass/Volume

D = M/V.............................. Equation 1

Where D = Density of the substance, M = mass of the substance, V = Volume of the subtance.

Make M the subject of the equation

M = D×V ............................ Equation 2

Given: D = 1200 kg/m³, V = 3 m³.

Substitute these values into equation 2

M = 1200×3

M = 3600 kg.

Hence the mass of the substance is 3600 kg

4 0

3 years ago

It is 5.00 km from your home to the physics lab. As part of your physical fitness program, you could run that distance at 10.0 k

8_murik_8 [283]

Answer:

a. Walking burns up more energy.

b. 1740 kJ

c. This is because more intense exercise releases a lot of energy in a short period of time, whereas, less intense energy releases it energy gradually over a long period of time.

Explanation:

a. We know energy W = Pt where P = power and t = time.

Now for walking, t = d/v where d = distance = 5.00 km and v = speed = 3.00 km/hr and P = 290 W

So, t = d/v = 5.00 km/3.00 km/hr = 5/3 hr = 5/3 × 3600 s = 6000 s

W = Pt = 290 W × 6000 s = 1740000 = 1740 kJ

Now for running, t = d/v where d = distance = 5.00 km and v = speed = 10.00 km/hr

So, t = d/v = 5.00 km/10.00 km/hr = 0.5 hr = 0.5 × 3600 s = 1800 s and P = 700 W

W = Pt = 700 W × 1800 s = 1260000 = 1260 kJ

Since walking burns up 1740 kJ and running burns up 1260 kJ, walking burns up more energy.

b. It burns up 1740 kJ

c. This is because more intense exercise releases a lot of energy in a short period of time, whereas, less intense energy releases it energy gradually over a long period of time.

4 0

4 years ago

10. A hockey puck with mass 0.3 kg is sliding along ice that can be considered frictionless. The puck’s velocity is 20 m/s when

SVEN [57.7K]

Answer:

$d = \frac{v^2_i}{2a}= \frac{(20m/s)^2}{2* 3.43 m/s^2}=58.309m$

Explanation:

For this case we can use the second law of Newton given by:

$\sum F = ma$

The friction force on this case is defined as :

$F_f = \mu_k N = \mu_k mg$

Where N represent the normal force, $\mu_k$ the kinetic friction coeffient and a the acceleration.

For this case we can assume that the only force is the friction force and we have:

$F_f = ma$

Replacing the friction force we got:

$\mu_k mg = ma$

We can cancel the mass and we have:

$a = \mu_k g = 0.35 *9.8 \frac{m}{s^2}= 3.43 \frac{m}{s^2}$

And now we can use the following kinematic formula in order to find the distance travelled:

$v^2_f = v^2_i - 2ad$

Assuming the final velocity is 0 we can find the distance like this:

$d = \frac{v^2_i}{2a}= \frac{(20m/s)^2}{2* 3.43 m/s^2}=58.309m$

5 0

3 years ago

An atomic physicist determines that an atom is composed of 8 positively charged particles and has a mass of 15 amu. which is the

stellarik [79]

<span> 1.the atom has 7 neutrons and 8 protons....

because the positively charged particles are the protons ...and 8 is also the atomic number ...so number of neutrons can be calculated by subtracting </span>atomic number from the mass number...which gives us the neutrons 7 ...

Hope it helps !!!

5 0

3 years ago

Read 2 more answers

5. During an anti-bullying club meeting after school, a student mentions that a new student has joined your class at school. The

Oksana_A [137]

Answer:

a. Constant gossiping, and talking negative about a student could cause them to feel very very ill about their beliefs, their familly, school, clothes, etc. this scenario will make the student feel alienated.

b. The club should advise the students that they should not participate in these talks, allow them into their groups, and should try to talk people out of those conversations.

c. The advice will keep several kids pull away from talking negatively about the kid, help stop the ill intended gossip, and hopefully make them feel better.

5 0

3 years ago