JAMB Physics Past Questions & Answers - Page 161

801.

A structural engineer stood on a top of a building releasing a light and heavy object to the ground which of the following statement is true?(Neglect Air Resistance)

A.

Both the light and heavy subject reach the ground at the same time

B.

The light object get to the ground first before the heavy object

C.

The heavy object to the ground first before the light object

D.

None get to the ground first

Correct answer is A

(Neglect of Air resistance)

Note: Both objects reach the ground at the same time

802.

For a best result using temperature to achieve an accurate measurement, it is best to use

A.

Mercury thermometer

B.

gas thermometer

C.

clinical thermometer

D.

alcohol thermometer

Correct answer is B

A gas thermometers are more besting use to achieve an accurate temperature than others, such as liquid in glass thermometers such as mercury, clinical and alcohol thermometer

803.

If the mechanical advantage of a machine is 4. What is its ratio for LOAD to EFFORT?

A.

4:01

B.

1:04

C.

5:01

D.

2:01

Correct answer is A

Mechanical advantage (M.A) of a machine is the ratio of its load to effort

Mathematically

Mechanical advantage (M.A) = Load (L) ÷ Effort (E)

In symbol M.A = L/E

Note:Mechanical (advantages has no S.I unit)

If M.A = 4 then,

L/E = 4/1

The ratio of load to effort = 4 : 1 respectively

804.

If the velocity ratio of a machine is 5. What is its ratio of x and y?

A.

2 : 5

B.

1 : 5

C.

5 : 1

D.

3 : 1

Correct answer is C

Velocity Ratio (V.R) = distance moved by the effort (x)÷ distance moved by the load (y)

i.e. V.R = x/y

v. R = 5, x/y = ?

i.e x/y = 5/1; , where x = 5, y = 1

x : y = 5 : 1

805.

If a ball released from a height of 20m, How long would it take the ball to reach the ground? (assumes g = 10m/s)

A.

2sec

B.

3sec

C.

35sec

D.

2.4sec

Correct answer is A

Using the equation

S = ut + ½ gt2

H = s = 20m, t = ?

G =10m/s2, u = 0m/s

20 = 0 × t × ½ × 10 t

20 = 5t

i.e 5t2 = 20

t = 20/5 = 4

t = 4 (squaring both sides)

√ t2 = √4

= 2sec

∴ t = 2sec