Turn on thread page Beta
    • Thread Starter

    Stuck on this question:
    Three supermarket trolleys, each of mass 20 kg, are placed on a straight line. As these trolleys move they are not subject to any resistance to motion. The first one is set in motion so that it moves at a speed of 4.5 m s–1 towards the second trolley. It then collides with the second trolley. After this collision the two trolleys continue to move together along the straight line at constant speed until they collide with the third trolley. After this collision all three trolleys move together along the straight line.
    (a) Show that the speed of the two moving trolleys after the first collision is 2.25 m s–1.
    (b) Find the speed of the trolleys after the second collision.
    (c) After the second collision the combined trolleys are subject to a single, horizontal resistance force of magnitude 30 N.
    (i) Calculate the acceleration of the trolleys while this force acts.
    (ii) Find the distance, that the trolleys move after the second collision, before they come to rest.

    Have hit a brick wall at part c(i), (got 1.5m/s for b) For c is it just F=MA? If so is F just the 30N or does the 1.5m/s have some part in it?

    Yes, I think it is just F=ma using -30N as the resultant force
    (taking the trolleys' direction of motion as the positive direction)
The home of Results and Clearing


people online now


students helped last year

University open days

  1. London Metropolitan University
    Undergraduate Open Day Undergraduate
    Sat, 18 Aug '18
  2. Edge Hill University
    All Faculties Undergraduate
    Sat, 18 Aug '18
  3. Bournemouth University
    Clearing Open Day Undergraduate
    Sat, 18 Aug '18
A-level students - how do you feel about your results?
Help with your A-levels

All the essentials

The adventure begins mug

Student life: what to expect

What it's really like going to uni


Essay expert

Learn to write like a pro with our ultimate essay guide.

Uni match

Uni match

Our tool will help you find the perfect course for you

Study planner

Create a study plan

Get your head around what you need to do and when with the study planner tool.

Study planner

Resources by subject

Everything from mind maps to class notes.

Hands typing

Degrees without fees

Discover more about degree-level apprenticeships.

A student doing homework

Study tips from A* students

Students who got top grades in their A-levels share their secrets

Study help links and info

Can you help? Study help unanswered threadsRules and posting guidelines

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.