Physics questions and answers

Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

1,436.

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

1,437.

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

1,438.

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

1,439.

A zinc has a heat capacity of 40 J/K, what is the mass of the zinc, given that the specific heat of zinc is 380 J/kg k

A.

0.11kg

B.

0.12kg

C.

0.13kg

D.

0.14kg

Correct answer is A

Heat capacity (o) = mass (kg) specific heat of a substance (C2)

i.e Q = MC

where Q = 40 J/L, m = ?(380 J/Kgk)

40 = m × 380

m = 0.11kg (Approx)

1,440.

If a mango fruit dropped at a height of 50 meters. How long does it reach the ground? (take g = 10m/s2)

A.

2 sec

B.

3 sec

C.

4 sec

D.

3.2 sec

Correct answer is D

From S = ut + ½gt2

u = 0ms-1

50 = (0 × t) + ½(10)(t2)

50 = 5.0t2

t2 =50/5

t = √10

t = 3.2sec