# Physics Practice Test 5

Q. 1
What would be the dimensional formula for the ratio between acceleration due to gravity and gravitational constant?
• a. M2L-2
• b. M2L-1
• c. ML-2
• d. ML-1
• e. ML

• Explaination: Explanation: Acceleration due to gravity at Earth is expressed as
g = GM/R2 --------------- (1)
Since we have to find the dimensional formula for the ratio between g and G, equation 1 can be written as
(g/G) = (M/R2) ------------- (2)
Thus, dimensional formula g/G of can be found by calculating the dimensional formula for M/R2
Since, dimensional formula of M is M and R is L hence, equation 2 can be written as
(g/G) = (M/L2)
Or, (g/G) = ML-2
Thus, C is the correct answer option.
Q. 2
A car speeds up from 15 m/s to 27 m/s in 45 s. What would be the acceleration of the car?
• a. 0.15 m/s2
• b. 0.32 m/s2
• c. 0.38 m/s2
• d. 0.27 m/s2
• e. 0.4 m/s2

• Explaination: Explanation: Here the initial speed, the final speed and the time taken are given and so we can use the kinematic equation
v = u + at ----------- (1)
Putting these values in equation 1 we get
27 = 15 + a * 45
Or, a = 0.27 m/s2
Therefore, D is the correct answer option.
Q. 3
Consider the following conclusions based on Newton’s first law.
1. Acceleration will be zero for a body obeying Newton’s first law
2. A balanced force is required to keep a body at rest or to keep it moving with uniform speed
3. An unbalanced force is required to keep a body at rest or to keep it moving with uniform speed
Based on the conclusions above, which of the following statement(s) is/are true?
• a. 1
• b. 2
• c. 3
• d. Both 1 and 2
• e. All three 