- An air force jet flying with a speed of 335m/s went past an anti aircraft gun. How far is the aircraft 5secs later when the gun was fired.

A. 838m. B. 3350m. C. 670m. D. 1675m. E. 67m

Solution

V = 335m/s,. Time = 5secs,

Formula, V = distance/time ( since we’re asked to find distance)

Distance = velocity×time; 335×5

= 1675m - A train has an initial velocity of 44m/s and an acceleration of -4m/s². It’s velocity after 10 sec is

A. 2m/s. B. 4m/s. C. 8m/s. D. 12m/s. E. 16m/s

Solution

U(initial velocity) = 44m/s, a = -4m/s², t = 10secs

Formula, a = (v-u)/t

-4 = (v-44)/10 ;

-4×10 = v-44

-40 = v-44

-40+44 = v

V = 4m/s - If a car starts from rest and moves with a uniform acceleration of 10m/s² for ten seconds the distance, it covers in the last one second of motion is

A. 95m. B. 100m. C. 500m. D. 905m. E. 1000m

Solution

a,(acceleration) = 10m/s², t=10secs, last one second of motion = subtract 10-9 seconds

Starts from rest, u = 0

Distance for ten seconds

Find distance, S=ut+½at²

S = 0×10+½×10×10²

S = 0+½×10×100

S1 = 500m

Find distance, S=ut+½at²

S = 0×10+½×10×9²

S2 = 0+½×10×81

= 405m

S =( distance for ten seconds)-(distance for nine second)

S = 500-405

= 95m. (A)

4.The figure below (Fig. 1.13) shows the velocity-time graph of a car which starts from rest and is accelerated uniformly at the rate of 3m/s² for 5 seconds. It attains a velocity which is maintained for 1 minute. The car is then brought to rest by a uniform retardation after another 3 seconds. Calculate the total distance covered.

A. 900meters B. 1920meters C. 1020meters D. 960meters E. 860meters

Solution

A = 3m/s², t = 5secs

V = u+ at

=0 + 3×5

V = 15m/s²

S = ½(a+b) ×h

½ (60+68) ×15 = ½ (128) ×15

960m

- The graph below (Fig. 1.14) describes the motion of a particle. The acceleration of the particle during the motion is

A. 0.00ms–². B. 0.25ms–² C. 4.00ms–². D. 8.00ms–². E. 10.00ms–²

Solution

. The acceleration of the particle during the motion = change in y velocity (ms-2) / change in x time(t seconds) a = (10-2)/(2-0); = 8/2

4.00ms–³

- What is the average velocity of the sprinter whose velocity-time graph is shown in the figure below?

A. 85.0ms-1 B. 17.0ms-2 C. 8.0ms-2 D. 1.7ms-2

Solution

Velocity time graph for the object in the graph at acceleration is = 10-2 ⇛ 8ms-2

- The diagram below (Fig. 1.17) shows a velocity-time graph representing the motion of a car. Find the total distance covered during the acceleration and retardation periods of the motion.

A. 75m B. 150m C. 300m D. 375m

Solution

Change in time = T2-T1 ⇛ 10-0 ⇛ 10m/s

For acceleration, a = (v-u)/t; = (10-0)/10

a = 1m/s

distances 1, s = ut+1/2 at2

0×10+1/2 ×1v102 = 50m

For deceleration, a =(u-v)/t

Change in time = 45-40 ⇛ 5secs

Deceleration, a = (10-0)/5

2m/s

Distance 2, s = ut + ½ ×2×52

25m

Total distance = s1 + s2

75m

- A body falls freely under gravity ( g = 9.8m/s2) from a height of 40m on to the top of a platform 0.8m above the ground. It’s velocity on reaching the platform is

A. 784m/s B. 80m/s C. 78.4m/s D. 39.2m/s E. 27.7m/s

Solution

G = 9.8m/s2, height = 40m, total height = 40-0.8; = 39.2m

V2 = U2 + 2GS

V2 = 0 + 2×9.8×39.2

= 27.7m/s

9. The figure below (Fig. 1.13) shows the velocity-time graph of a car which starts from rest and is accelerated uniformly at the rate of 3m/s2 for 5 seconds. It attains a velocity which is maintained for 1 minute. The car is then brought to rest by a uniform retardation after another 3 seconds. Calculate the total distance covered.

A. 900meters B. 1920meters C. 1020meters D. 960meters E. 860meters

Solution

A = 3m/s2, t = 5secs

V = u+ at

=0 + 3×5

V = 15m/s2

S = ½(a+b) ×h

½ (60+68) ×15 = ½ (128) ×15

960m

- The graph below (Fig. 1.14) describes the motion of a particle. The acceleration of the particle during the motion is

A. 0.00ms-². B. 0.25ms-². C. 4.00ms-2² D. 8.00ms-² E. 10.00ms-²

Solution

. The acceleration of the particle during the motion = change in y velocity (ms-2) / change in x time(t seconds) a = (10-2)/(2-0); = 8/2

4.00ms-²b

- What is the average velocity of the sprinter whose velocity-time graph is shown in the figure above?

A. 85.0ms-1 B. 17.0ms-2 C. 8.0ms-2 D. 1.7ms-2

Solution

Velocity time graph for the object in the graph at acceleration is = 10-2 ⇛ 8ms-² - The diagram above (Fig. 1.17) shows a velocity-time graph representing the motion of a car. Find the total distance covered during the acceleration and retardation periods of the motion.

A. 75m B. 150m C. 300m D. 375m

Solution

Change in time = T2-T1 ⇛ 10-0 ⇛ 10m/s

For acceleration, a = (v-u)/t; = (10-0)/10

a = 1m/s

distances 1, s = ut+1/2 at2

0×10+1/2 ×1v102 = 50m

For deceleration, a =(u-v)/t

Change in time = 45-40 ⇛ 5secs

Deceleration, a = (10-0)/5

2m/s

Distance 2, s = ut + ½ ×2×52

25m

Total distance = s1 + s2

75m

- A body falls freely under gravity ( g = 9.8m/s2) from a height of 40m on to the top of a platform 0.8m above the ground. It’s velocity on reaching the platform is

A. 784m/s B. 80m/s C. 78.4m/s D. 39.2m/s E. 27.7m/s

Solution

G = 9.8m/s2, height = 40m, total height = 40-0.8; = 39.2m

V2 = U2 + 2GS

V2 = 02 + 2×9.8×39.2

= 27.7m/s

- A body falls freely under gravity ( g = 9.8m/s2) from a height of 40m on to the top of a platform 0.8m above the ground. It’s velocity on reaching the platform is

A. 784m/s B. 80m/s C. 78.4m/s D. 39.2m/s E. 27.7m/s

Solution

G = 9.8m/s2, height = 40m, total height = 40-0.8; = 39.2m

V2 = U2 + 2GS

V2 = 02 + 2×9.8×39.2

= 27.7m/s - The diagram below (Fig 1.18) shows the velocity-time graph of a vehicle. Its acceleration and retardation respectively are.

A. 8.0ms-², 4.0 ms–². B.. 4.0 ms-², 8.0 ms-² C. 4.0 ms-², 2.0 ms-². D. 2.0 ms-² , 4.0 ms-²

Solution

At acceleration the velocity-time graph = change in velocity (m/s)/ change in time ( seconds)

(V2-V1)/(T1-T2) = (80-0)/(20-0)

4m/s²

Retardation of the velocity-time graph = change in velocity (m/s)/ change in time ( seconds)

(80-0)/(90-50) = 2m/s²

Its acceleration and retardation respectively are 4.0 ms-², 2.0 ms-²

- A mango fruit drops from a branch 10m above the ground, just before hitting the ground its velocity is

A. 10-1 B. 10/-1 C. 100-1 D. 5-1

Solution

The answer is 10-1 - A palm fruit dropped to the ground from the top of a tree 45m tall. How long does it take to reach the ground? [g = 10ms-2]

A. A. 9s B. 4.5s C. 6s D. 7.5s E. 3s

Solution

H = ut + 1/2gt2

45 =0×t + ½ ×10×t2

t2 = 9

t = 3 - A small metal ball is thrown vertically upwards from the top of a tower with an initial velocity of 20ms-1, if the ball took a total of 6 seconds to reach the ground level, determine the height of the tower. (g = 10ms-2)

A. 60m B. 60m D. 100m D. 20m

Solution

Time = 6 seconds, u = 20ms-2

V2 = U2 + 2gh

02 = 202 + 2×10×h

H = 400/20

H = 20m - In free fall, a body of mass 1k drops from a height of 125m from rest in 5 seconds. How long will it take another body of mass 2kg to fall from rest, from the same height? [g – 10ms-2]

A. 5s B. 10s c. 12s D. 15s

Solution

Since it is a free fall, using the law of gravity the answer will still be 5s

Answer = 5s - Two particles X and Y starting from rest cover the same distance. The acceleration of X is twice that of Y. the ratio of the time taken by X to that taken by Y is?

A. ½ n B. 2 C. 1/ D. E. 4

Solution

The acceleration of X is twice that of Y = 1/ - A bullet fired vertically upward from a gun held 2.0m above the ground reaches its maximum height in 4.0s. Calculate its initial velocity. (g = 10ms-2)

A. 10ms-1 B. 8 ms-1 C. 20 ms-1 D. 40 ms-1

Solution

Since it’s vertically upward, U = V + at

U = 0 + 10×4

U = 40 ms-1 - What is the acceleration between two points on a velocity-time graph which has coordinates (10s, 15 ms-1 ) and (20s, 35 ms-1 )?

A. 1.75 ms-2 B. 3.50 ms-2 C. 1.00 ms-2 D. 2.00 ms-2

Solution

Acceleration = change in velocity (m/s)/ change in time ( seconds)

(35-15)/ (20-10) = 20/10

2 ms-2 - A car accelerates uniformly from rest at 4 ms-2. How far will it travel in fifth complete second?

A. 100m B. 50m C. 32m D. 18m

Solution

travel in fifth complete second = T5-T4

S = ut + ½ at2

S = 0×t + ½ ×4×(52-42)

S = ½ × 4×(25-16)

S = 2×9

S = 18m