Twenty Questions

Kinematics

Twenty Questions

1 2 3 4 5

6 7 8 9 10

11 12 13 14 15

16 17 18 19 20

1. What formula relates speed, distance and time?

• v = d / t• speed = distance/time

2. What is deceleration?

• an object slowing down.

• negative acceleration.

3. What is the difference between scalars and vectors?

• scalar has magnitude, only.

• vector has both magnitude and direction.

4. Calculate distance travelled.

• d = area under v-t graph• d = ½ bh + lb + lb + ½

bh• d =½5x4 +4x5 +13x8

+½2x8• d = 10 + 20 + 104 + 8• d = 142m

v(m/s)

t(s)5

8

4

200 18

5. A girls jogs 2km North, then turns & jogs 1.6km South. She does this in 10mins.What is her speed?

• v = d/t• v = 3600/600• v = 6ms-1

• v = s/t• v = 400/600• v = 0.67ms-1 North

6. A girls jogs 2km North, then turns & jogs 1.6km South. She does this in 10mins.What is her velocity?

7. A train accelerates from 20ms-1 to 30ms-1 in 2.5s.What is the trains acceleration?

• a = v - u = 30 – 20 t 2.5• a =4ms-2

8. Describe the motion between B and C.

• The vehicle travels at constant speed.

• Zero acceleration.

v(m/s)

t(s)DA

B C

9. A Harley Davidson accelerates, from rest, at 2.5ms-2 to 30ms-1 in 10s.What was the bike’s initial speed?

• a = v - u t• 2.5 = 30 – u 2• u =25ms-1

10. Calculate the acceleration between 18s and 20s.

• a = v - u = 0 – 8 t 2• a =-4ms-2

v(m/s)

t(s)5

8

4

200 18

11. A cross-country runner runs 200m North then 1km East.What is the runners displacement?

Scale 1cm:200m

s = 1020m at 79o

a2 = b2 + c2

• a = √2002+10002

a = 1019.80m

• s = 1019.80m at 078.7o

tanθ = O/A = 1000 ÷ 200 = 5

• θ = 78.7

12. A bus accelerates at 3ms-2 from rest to 30ms-1. How long does this take?

• a = v - u t

• t = v - u = 30 – 0 a 3• t = 10s

13. A bike accelerates at 5m/s2 from rest for 15s. What is it’s final speed?

• a = v - u t

• v = u + at = 0 + 5x15• v = 75m/s

14. Describe the motion between A&B.

• Vehicle is accelerating.

v(m/s)

t(s)DA

B C

15. What is the formula for velocity?

• v = s / t• velocity =

displacement time

16.Describe the motion between C&D.

v(m/s)

t(s)DA

B C

• The vehicle decelerates.

17. How is the apparatus shown, used to find the instantaneous speed of the trolley at the bottom of the ramp?

• Use light gate and timer to find time, t.• Length of mask, d. • v = d / t

Light gate

Timer

Ramp

Trolley

18. What is the acceleration of an object moving at a steady speed?

• 0ms-2

19. Which car has the smallest acceleration?

• Renault.

Car Time for 0-60 Max speedPorsche 6.3 138

Ford 12.8 125Renault 15.7 110Bentley 10.5 129

20. Calculate the acceleration.

a = v - u = 8 – 4 t 5

a = 0.8ms-2

v(m/s)

t(s)5

8

4

200 18