Calculating the time of stopping distance

In summary, the conversation was about a person struggling with a physics topic and needing help with calculating the deceleration and force on a child in a moving car. They were unsure of which formula to use and were considering using a suvat equation, but were not sure if it would work. They also mentioned using the kinematic equation and Newton's 2nd law. Ultimately, they found the answer and thanked the expert for support.
  • #1
chaz699
19
0
well I'm struggling with a level physics and need some help with a new topic area we're studying

the problem is

a moving car t velocity of 20 ms(-1) brakes to a standstill in a distance of 40m, a child of mass 15kg is sitting in a forward facing child car seat fitted to the back-seat of the car

calculate (1) the deceleration (2) the force on the child


i always thought to calculate the deceleration is braking distance/ mass but the only mass given is that of the child and surely the car will way more than that, hence why i don't understand what formula to use, is it using suvat? if so i can't find a suvat formula with only s U and v, its driving me mad ( no pun intended)



for the second part of the question I haven't been told any information on how to work it out but is the formula t= 2s/U + v (t is time, s is distance/displacement, U is initial velocity and v is final velocity
 
Physics news on Phys.org
  • #2
chaz699 said:
well I'm struggling with a level physics and need some help with a new topic area we're studying

the problem is

a moving car t velocity of 20 ms(-1) brakes to a standstill in a distance of 40m, a child of mass 15kg is sitting in a forward facing child car seat fitted to the back-seat of the car

calculate (1) the deceleration (2) the force on the child


i always thought to calculate the deceleration is braking distance/ mass but the only mass given is that of the child and surely the car will way more than that, hence why i don't understand what formula to use, is it using suvat? if so i can't find a suvat formula with only s U and v, its driving me mad ( no pun intended)
I don't know why you were thinking that distance/mass equals acceleration. Erase that thought. What about the kinematic equation vf^2 = vo^2 + 2as? You didn't do enough searching on your suavat's.
for the second part of the question I haven't been told any information on how to work it out but is the formula t= 2s/U + v (t is time, s is distance/displacement, U is initial velocity and v is final velocity
How about using Newton's 2nd law?
 
  • #3
i think i have it now

thanks (i found out Newtons second law about 2 minutes before u posted, and the suvat question i just found,) thanks for providing me with support so i avoidied doubting myself
 

FAQ: Calculating the time of stopping distance

How do I calculate stopping distance?

Stopping distance can be calculated by adding together the thinking distance and braking distance. The thinking distance is the distance traveled by the vehicle in the time it takes for the driver to react to a hazard, while the braking distance is the distance traveled during the time it takes for the vehicle to come to a complete stop after the brakes are applied.

What factors affect stopping distance?

Stopping distance is affected by factors such as speed, road conditions, and vehicle weight. The higher the speed, the longer the stopping distance will be. Wet or icy roads can also increase stopping distance, as well as a heavier vehicle or a vehicle carrying a heavy load.

How does speed affect stopping distance?

Speed has a direct impact on stopping distance. The faster a vehicle is traveling, the longer the stopping distance will be. This is because the vehicle has more momentum and requires more time and distance to come to a complete stop.

Is there a formula for calculating stopping distance?

Yes, the formula for calculating stopping distance is: stopping distance = thinking distance + braking distance. The thinking distance can be calculated by multiplying the speed by the reaction time in seconds. The braking distance can be calculated by dividing the speed by the braking deceleration and then multiplying by the speed again.

How can I reduce stopping distance?

To reduce stopping distance, it is important to maintain a safe and appropriate speed for the road and weather conditions. You should also regularly check and maintain your vehicle's brakes, tires, and suspension to ensure they are in good working condition. Keeping a proper following distance from other vehicles can also help reduce stopping distance in case of sudden braking situations.

Similar threads

Help with question on motion: Avoiding a rear-end collision
Replies
6
Views
2K
Relating acceleration to distance and time
Replies
5
Views
2K
What distance will be covered before coming to stop?
Replies
12
Views
651
How does tire pressure affect distance traveled by a bicycle coasting to a stop?
Replies
31
Views
2K
Mechanics: Motion of Two Connected Vehicles
Replies
3
Views
948
Motion problem: motorist's braking time including reaction time
Replies
1
Views
1K
Calculating Stopping Distance for Car Traveling at 3.0v
Replies
1
Views
7K
Moving in a straight line with multiple constraints
3
Replies
98
Views
5K
Reaction time while stopping a car
Replies
29
Views
3K
Calculating the Stopping distance
Replies
7
Views
3K

Hot Threads

Recent Insights

Back
Top