# How long does it take it increase speed?

• RanHam335
In summary, to determine the time it takes for a freight train with a mass of 1.2e+7 kg to increase its speed from rest to 82 km/h, the formula (mass*velocity)/force is used. After converting the speed from km/h to m/s, the velocity is calculated to be 820/36 m/s. By plugging in the values of mass, velocity, and force, the time is calculated to be approximately 5.1e-2 minutes. However, this may seem like a small amount of time to increase the speed from 0 to 82 km/h.
RanHam335

## Homework Statement

A freight train has a mass of 1.2e+7 kg. If the locomotive can exert a constant pull of 8.4e+5 N, how long does it take to increase the speed of the train from rest to 82 km/h?

## Homework Equations

(mass*velocity)/time=force

## The Attempt at a Solution

(1.2e+7 * 82)/h = 8.4e+5

i solved for h
h = (8.4e+5)/(9.84e+8)
h = 8.54e-4

then i had to convert from hours to min.
8.54e-4*60

so i got
5.1e-2 min

this is my first time posting on this forum so i hope i followed the right format.

82km/h = $\frac{82*1000m}{3600s}$

can you explain the above?

I just converted the speed from km/h to m/s which is usually what you should do.

82km/h

in 1h train travels 82km
=> in 1h train travels 82*1000m
in 3600s train travels 82000m
in 1s train travels 82000/3600 m

therefore the velocity in m/s is 820/36

that doesn't answer my question, i think I am messing up on the formula. I have one submission left so i don't want to risk it

$$F=\frac{mv}{t} \Rightarrow t=\frac{mv}{F}$$

$$t=\frac{(1.2*10^7 kg)*((\frac{82000}{3600} ms^-1)}{8.4*10^5 N}$$

Can you calculate now?

But your answer was $5.1*10^{-2}$minutes. Doesn't that seem like a small amount of time to go from 0 to 82km/h ?

## 1. How long does it take to increase speed?

The time it takes to increase speed varies depending on the object or organism in question, as well as the method used to increase speed. Some objects, such as a car, may have a specific acceleration rate that can be calculated. For organisms, it may depend on factors such as training and physical abilities.

## 2. Can speed be increased quickly?

In some cases, speed can be increased quickly through the use of external forces such as a motor or propulsion system. However, for natural motion, increasing speed quickly may not be possible as it requires overcoming inertia and building momentum.

## 3. What factors affect the time it takes to increase speed?

The time it takes to increase speed can be affected by various factors such as the object's mass, the force applied, and any resistance or obstacles in the way. For organisms, factors such as muscle strength, agility, and technique can also play a role.

## 4. Is there a limit to how fast an object can increase its speed?

Yes, there is a limit to how fast an object can increase its speed. This is known as the speed of light, which is the maximum speed at which all matter and information in the universe can travel. For objects on earth, the limit may be determined by physical constraints such as air resistance or the capabilities of the object's propulsion system.

## 5. How can speed be increased over time?

Speed can be increased over time through consistent training and conditioning. This allows the body or object to build muscle strength, endurance, and technique, which can result in increased speed. Additionally, technological advancements and improvements in design can also contribute to increasing speed over time.

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